v2.4.5

for now only used for keys passed to `-c` or `-b`.

README.md

@@ -87,6 +87,10 @@ The available options are:
                      Note that currently not *all* comments can be kept when
                      compression is on, because of dead code removal or
                      cascading statements into sequences.               [string]
+  --preamble         Preamble to prepend to the output.  You can use this to
+                     insert a comment, for example for licensing information.
+                     This will not be parsed, but the source map will adjust
+                     for its presence.
   --stats            Display operations run time on STDERR.            [boolean]
   --acorn            Use Acorn for parsing.                            [boolean]
   --spidermonkey     Assume input files are SpiderMonkey AST format (as JSON).
@@ -184,35 +188,67 @@ you can pass a comma-separated list of options.  Options are in the form
 to set `true`; it's effectively a shortcut for `foo=true`).
 
 - `sequences` -- join consecutive simple statements using the comma operator
+
 - `properties` -- rewrite property access using the dot notation, for
   example `foo["bar"] → foo.bar`
+
 - `dead_code` -- remove unreachable code
+
 - `drop_debugger` -- remove `debugger;` statements
+
 - `unsafe` (default: false) -- apply "unsafe" transformations (discussion below)
+
 - `conditionals` -- apply optimizations for `if`-s and conditional
   expressions
+
 - `comparisons` -- apply certain optimizations to binary nodes, for example:
   `!(a <= b) → a > b` (only when `unsafe`), attempts to negate binary nodes,
   e.g. `a = !b && !c && !d && !e → a=!(b||c||d||e)` etc.
+
 - `evaluate` -- attempt to evaluate constant expressions
+
 - `booleans` -- various optimizations for boolean context, for example `!!a
   ? b : c → a ? b : c`
+
 - `loops` -- optimizations for `do`, `while` and `for` loops when we can
   statically determine the condition
+
 - `unused` -- drop unreferenced functions and variables
+
 - `hoist_funs` -- hoist function declarations
+
 - `hoist_vars` (default: false) -- hoist `var` declarations (this is `false`
   by default because it seems to increase the size of the output in general)
+
 - `if_return` -- optimizations for if/return and if/continue
+
 - `join_vars` -- join consecutive `var` statements
+
 - `cascade` -- small optimization for sequences, transform `x, x` into `x`
   and `x = something(), x` into `x = something()`
+
 - `warnings` -- display warnings when dropping unreachable code or unused
   declarations etc.
+
 - `negate_iife` -- negate "Immediately-Called Function Expressions"
   where the return value is discarded, to avoid the parens that the
   code generator would insert.
 
+- `pure_getters` -- the default is `false`.  If you pass `true` for
+  this, UglifyJS will assume that object property access
+  (e.g. `foo.bar` or `foo["bar"]`) doesn't have any side effects.
+
+- `pure_funcs` -- default `null`.  You can pass an array of names and
+  UglifyJS will assume that those functions do not produce side
+  effects.  DANGER: will not check if the name is redefined in scope.
+  An example case here, for instance `var q = Math.floor(a/b)`.  If
+  variable `q` is not used elsewhere, UglifyJS will drop it, but will
+  still keep the `Math.floor(a/b)`, not knowing what it does.  You can
+  pass `pure_funcs: [ 'Math.floor' ]` to let it know that this
+  function won't produce any side effect, in which case the whole
+  statement would get discarded.  The current implementation adds some
+  overhead (compression will be slower).
+
 ### The `unsafe` option
 
 It enables some transformations that *might* break code logic in certain
@@ -225,7 +261,7 @@ when this flag is on:
 - `String(exp)` or `exp.toString()` → `"" + exp`
 - `new Object/RegExp/Function/Error/Array (...)` → we discard the `new`
 - `typeof foo == "undefined"` → `foo === void 0`
-- `void 0` → `"undefined"` (if there is a variable named "undefined" in
+- `void 0` → `undefined` (if there is a variable named "undefined" in
   scope; we do it because the variable name will be mangled, typically
   reduced to a single character).
 
@@ -296,6 +332,10 @@ can pass additional arguments that control the code output:
   you pass `false` then whenever possible we will use a newline instead of a
   semicolon, leading to more readable output of uglified code (size before
   gzip could be smaller; size after gzip insignificantly larger).
+- `preamble` (default `null`) -- when passed it must be a string and
+  it will be prepended to the output literally.  The source map will
+  adjust for this text.  Can be used to insert a comment containing
+  licensing information, for example.
 
 ### Keeping copyright notices or other comments
 

bin/uglifyjs

@@ -48,6 +48,10 @@ You can optionally pass one of the following arguments to this flag:\n\
 Note that currently not *all* comments can be kept when compression is on, \
 because of dead code removal or cascading statements into sequences.")
 
+    .describe("preamble", "Preamble to prepend to the output.  You can use this to insert a \
+comment, for example for licensing information.  This will not be \
+parsed, but the source map will adjust for its presence.")
+
     .describe("stats", "Display operations run time on STDERR.")
     .describe("acorn", "Use Acorn for parsing.")
     .describe("spidermonkey", "Assume input files are SpiderMonkey AST format (as JSON).")
@@ -58,6 +62,7 @@ You need to pass an argument to this option to specify the name that your module
     .describe("lint", "Display some scope warnings")
     .describe("v", "Verbose")
     .describe("V", "Print version number and exit.")
+    .describe("noerr", "Don't throw an error for unknown options in -c, -b or -m.")
 
     .alias("p", "prefix")
     .alias("o", "output")
@@ -92,6 +97,7 @@ You need to pass an argument to this option to specify the name that your module
     .boolean("spidermonkey")
     .boolean("lint")
     .boolean("V")
+    .boolean("noerr")
 
     .wrap(80)
 
@@ -100,6 +106,12 @@ You need to pass an argument to this option to specify the name that your module
 
 normalize(ARGS);
 
+if (ARGS.noerr) {
+    UglifyJS.DefaultsError.croak = function(msg, defs) {
+        sys.error("WARN: " + msg);
+    };
+}
+
 if (ARGS.version || ARGS.V) {
     var json = require("../package.json");
     sys.puts(json.name + ' ' + json.version);
@@ -134,7 +146,8 @@ if (ARGS.r) {
 }
 
 var OUTPUT_OPTIONS = {
-    beautify: BEAUTIFY ? true : false
+    beautify: BEAUTIFY ? true : false,
+    preamble: ARGS.preamble || null,
 };
 
 if (ARGS.screw_ie8) {
@@ -251,17 +264,26 @@ async.eachLimit(files, 1, function (file, cb) {
             else if (ARGS.acorn) {
                 TOPLEVEL = acorn.parse(code, {
                     locations     : true,
-                    trackComments : true,
                     sourceFile    : file,
                     program       : TOPLEVEL
                 });
             }
             else {
-                TOPLEVEL = UglifyJS.parse(code, {
-                    filename   : file,
-                    toplevel   : TOPLEVEL,
-                    expression : ARGS.expr,
-                });
+                try {
+                    TOPLEVEL = UglifyJS.parse(code, {
+                        filename   : file,
+                        toplevel   : TOPLEVEL,
+                        expression : ARGS.expr,
+                    });
+                } catch(ex) {
+                    if (ex instanceof UglifyJS.JS_Parse_Error) {
+                        sys.error("Parse error at " + file + ":" + ex.line + "," + ex.col);
+                        sys.error(ex.message);
+                        sys.error(ex.stack);
+                        process.exit(1);
+                    }
+                    throw ex;
+                }
             };
         });
         cb();
@@ -367,7 +389,7 @@ function getOptions(x, constants) {
     if (x !== true) {
         var ast;
         try {
-            ast = UglifyJS.parse(x);
+            ast = UglifyJS.parse(x, { expression: true });
         } catch(ex) {
             if (ex instanceof UglifyJS.JS_Parse_Error) {
                 sys.error("Error parsing arguments in: " + x);
@@ -375,8 +397,6 @@ function getOptions(x, constants) {
             }
         }
         ast.walk(new UglifyJS.TreeWalker(function(node){
-            if (node instanceof UglifyJS.AST_Toplevel) return; // descend
-            if (node instanceof UglifyJS.AST_SimpleStatement) return; // descend
             if (node instanceof UglifyJS.AST_Seq) return; // descend
             if (node instanceof UglifyJS.AST_Assign) {
                 var name = node.left.print_to_string({ beautify: false }).replace(/-/g, "_");
@@ -386,6 +406,11 @@ function getOptions(x, constants) {
                 ret[name] = value;
                 return true;    // no descend
             }
+            if (node instanceof UglifyJS.AST_Symbol || node instanceof UglifyJS.AST_Binary) {
+                var name = node.print_to_string({ beautify: false }).replace(/-/g, "_");
+                ret[name] = true;
+                return true;    // no descend
+            }
             sys.error(node.TYPE)
             sys.error("Error parsing arguments in: " + x);
             process.exit(1);

lib/ast.js

@@ -197,6 +197,10 @@ var AST_LabeledStatement = DEFNODE("LabeledStatement", "label", {
     }
 }, AST_StatementWithBody);
 
+var AST_IterationStatement = DEFNODE("IterationStatement", null, {
+    $documentation: "Internal class.  All loops inherit from it."
+}, AST_StatementWithBody);
+
 var AST_DWLoop = DEFNODE("DWLoop", "condition", {
     $documentation: "Base class for do/while statements",
     $propdoc: {
@@ -208,7 +212,7 @@ var AST_DWLoop = DEFNODE("DWLoop", "condition", {
             this.body._walk(visitor);
         });
     }
-}, AST_StatementWithBody);
+}, AST_IterationStatement);
 
 var AST_Do = DEFNODE("Do", null, {
     $documentation: "A `do` statement",
@@ -233,7 +237,7 @@ var AST_For = DEFNODE("For", "init condition step", {
             this.body._walk(visitor);
         });
     }
-}, AST_StatementWithBody);
+}, AST_IterationStatement);
 
 var AST_ForIn = DEFNODE("ForIn", "init name object", {
     $documentation: "A `for ... in` statement",
@@ -249,7 +253,7 @@ var AST_ForIn = DEFNODE("ForIn", "init name object", {
             this.body._walk(visitor);
         });
     }
-}, AST_StatementWithBody);
+}, AST_IterationStatement);
 
 var AST_With = DEFNODE("With", "expression", {
     $documentation: "A `with` statement",
@@ -367,7 +371,7 @@ var AST_Lambda = DEFNODE("Lambda", "name argnames uses_arguments", {
 }, AST_Scope);
 
 var AST_Accessor = DEFNODE("Accessor", null, {
-    $documentation: "A setter/getter function"
+    $documentation: "A setter/getter function.  The `name` property is always null."
 }, AST_Lambda);
 
 var AST_Function = DEFNODE("Function", null, {
@@ -752,7 +756,7 @@ var AST_Object = DEFNODE("Object", "properties", {
 var AST_ObjectProperty = DEFNODE("ObjectProperty", "key value", {
     $documentation: "Base class for literal object properties",
     $propdoc: {
-        key: "[string] the property name; it's always a plain string in our AST, no matter if it was a string, number or identifier in original code",
+        key: "[string] the property name converted to a string for ObjectKeyVal.  For setters and getters this is an arbitrary AST_Node.",
         value: "[AST_Node] property value.  For setters and getters this is an AST_Function."
     },
     _walk: function(visitor) {
@@ -821,7 +825,11 @@ var AST_SymbolCatch = DEFNODE("SymbolCatch", null, {
 var AST_Label = DEFNODE("Label", "references", {
     $documentation: "Symbol naming a label (declaration)",
     $propdoc: {
-        references: "[AST_LabelRef*] a list of nodes referring to this label"
+        references: "[AST_LoopControl*] a list of nodes referring to this label"
+    },
+    initialize: function() {
+        this.references = [];
+        this.thedef = this;
     }
 }, AST_Symbol);
 
@@ -968,21 +976,15 @@ TreeWalker.prototype = {
     },
     loopcontrol_target: function(label) {
         var stack = this.stack;
-        if (label) {
-            for (var i = stack.length; --i >= 0;) {
-                var x = stack[i];
-                if (x instanceof AST_LabeledStatement && x.label.name == label.name) {
-                    return x.body;
-                }
-            }
-        } else {
-            for (var i = stack.length; --i >= 0;) {
-                var x = stack[i];
-                if (x instanceof AST_Switch
-                    || x instanceof AST_For
-                    || x instanceof AST_ForIn
-                    || x instanceof AST_DWLoop) return x;
+        if (label) for (var i = stack.length; --i >= 0;) {
+            var x = stack[i];
+            if (x instanceof AST_LabeledStatement && x.label.name == label.name) {
+                return x.body;
             }
+        } else for (var i = stack.length; --i >= 0;) {
+            var x = stack[i];
+            if (x instanceof AST_Switch || x instanceof AST_IterationStatement)
+                return x;
         }
     }
 };

lib/compress.js

@@ -66,6 +66,8 @@ function Compressor(options, false_by_default) {
         join_vars     : !false_by_default,
         cascade       : !false_by_default,
         side_effects  : !false_by_default,
+        pure_getters  : false,
+        pure_funcs    : null,
         negate_iife   : !false_by_default,
         screw_ie8     : false,
 
@@ -83,22 +85,16 @@ merge(Compressor.prototype, {
     },
     before: function(node, descend, in_list) {
         if (node._squeezed) return node;
+        var was_scope = false;
         if (node instanceof AST_Scope) {
-            node.drop_unused(this);
             node = node.hoist_declarations(this);
+            was_scope = true;
         }
         descend(node, this);
         node = node.optimize(this);
-        if (node instanceof AST_Scope) {
-            // dead code removal might leave further unused declarations.
-            // this'll usually save very few bytes, but the performance
-            // hit seems negligible so I'll just drop it here.
-
-            // no point to repeat warnings.
-            var save_warnings = this.options.warnings;
-            this.options.warnings = false;
+        if (was_scope && node instanceof AST_Scope) {
             node.drop_unused(this);
-            this.options.warnings = save_warnings;
+            descend(node, this);
         }
         node._squeezed = true;
         return node;
@@ -324,7 +320,7 @@ merge(Compressor.prototype, {
                                || (ab instanceof AST_Continue && self === loop_body(lct))
                                || (ab instanceof AST_Break && lct instanceof AST_BlockStatement && self === lct))) {
                         if (ab.label) {
-                            remove(ab.label.thedef.references, ab.label);
+                            remove(ab.label.thedef.references, ab);
                         }
                         CHANGED = true;
                         var body = as_statement_array(stat.body).slice(0, -1);
@@ -346,7 +342,7 @@ merge(Compressor.prototype, {
                                || (ab instanceof AST_Continue && self === loop_body(lct))
                                || (ab instanceof AST_Break && lct instanceof AST_BlockStatement && self === lct))) {
                         if (ab.label) {
-                            remove(ab.label.thedef.references, ab.label);
+                            remove(ab.label.thedef.references, ab);
                         }
                         CHANGED = true;
                         stat = stat.clone();
@@ -385,7 +381,7 @@ merge(Compressor.prototype, {
                              && loop_body(lct) === self) || (stat instanceof AST_Continue
                                                              && loop_body(lct) === self)) {
                             if (stat.label) {
-                                remove(stat.label.thedef.references, stat.label);
+                                remove(stat.label.thedef.references, stat);
                             }
                         } else {
                             a.push(stat);
@@ -630,14 +626,14 @@ merge(Compressor.prototype, {
         // elements.  If the node has been successfully reduced to a
         // constant, then the second element tells us the value;
         // otherwise the second element is missing.  The first element
-        // of the array is always an AST_Node descendant; when
+        // of the array is always an AST_Node descendant; if
         // evaluation was successful it's a node that represents the
-        // constant; otherwise it's the original node.
+        // constant; otherwise it's the original or a replacement node.
         AST_Node.DEFMETHOD("evaluate", function(compressor){
             if (!compressor.option("evaluate")) return [ this ];
             try {
-                var val = this._eval(), ast = make_node_from_constant(compressor, val, this);
-                return [ best_of(ast, this), val ];
+                var val = this._eval(compressor);
+                return [ best_of(make_node_from_constant(compressor, val, this), this), val ];
             } catch(ex) {
                 if (ex !== def) throw ex;
                 return [ this ];
@@ -653,8 +649,10 @@ merge(Compressor.prototype, {
             // places too. :-( Wish JS had multiple inheritance.
             throw def;
         });
-        function ev(node) {
-            return node._eval();
+        function ev(node, compressor) {
+            if (!compressor) throw new Error("Compressor must be passed");
+
+            return node._eval(compressor);
         };
         def(AST_Node, function(){
             throw def;          // not constant
@@ -662,69 +660,69 @@ merge(Compressor.prototype, {
         def(AST_Constant, function(){
             return this.getValue();
         });
-        def(AST_UnaryPrefix, function(){
+        def(AST_UnaryPrefix, function(compressor){
             var e = this.expression;
             switch (this.operator) {
-              case "!": return !ev(e);
+              case "!": return !ev(e, compressor);
               case "typeof":
                 // Function would be evaluated to an array and so typeof would
                 // incorrectly return 'object'. Hence making is a special case.
                 if (e instanceof AST_Function) return typeof function(){};
 
-                e = ev(e);
+                e = ev(e, compressor);
 
                 // typeof <RegExp> returns "object" or "function" on different platforms
                 // so cannot evaluate reliably
                 if (e instanceof RegExp) throw def;
 
                 return typeof e;
-              case "void": return void ev(e);
-              case "~": return ~ev(e);
+              case "void": return void ev(e, compressor);
+              case "~": return ~ev(e, compressor);
               case "-":
-                e = ev(e);
+                e = ev(e, compressor);
                 if (e === 0) throw def;
                 return -e;
-              case "+": return +ev(e);
+              case "+": return +ev(e, compressor);
             }
             throw def;
         });
-        def(AST_Binary, function(){
+        def(AST_Binary, function(c){
             var left = this.left, right = this.right;
             switch (this.operator) {
-              case "&&"         : return ev(left) &&         ev(right);
-              case "||"         : return ev(left) ||         ev(right);
-              case "|"          : return ev(left) |          ev(right);
-              case "&"          : return ev(left) &          ev(right);
-              case "^"          : return ev(left) ^          ev(right);
-              case "+"          : return ev(left) +          ev(right);
-              case "*"          : return ev(left) *          ev(right);
-              case "/"          : return ev(left) /          ev(right);
-              case "%"          : return ev(left) %          ev(right);
-              case "-"          : return ev(left) -          ev(right);
-              case "<<"         : return ev(left) <<         ev(right);
-              case ">>"         : return ev(left) >>         ev(right);
-              case ">>>"        : return ev(left) >>>        ev(right);
-              case "=="         : return ev(left) ==         ev(right);
-              case "==="        : return ev(left) ===        ev(right);
-              case "!="         : return ev(left) !=         ev(right);
-              case "!=="        : return ev(left) !==        ev(right);
-              case "<"          : return ev(left) <          ev(right);
-              case "<="         : return ev(left) <=         ev(right);
-              case ">"          : return ev(left) >          ev(right);
-              case ">="         : return ev(left) >=         ev(right);
-              case "in"         : return ev(left) in         ev(right);
-              case "instanceof" : return ev(left) instanceof ev(right);
+              case "&&"         : return ev(left, c) &&         ev(right, c);
+              case "||"         : return ev(left, c) ||         ev(right, c);
+              case "|"          : return ev(left, c) |          ev(right, c);
+              case "&"          : return ev(left, c) &          ev(right, c);
+              case "^"          : return ev(left, c) ^          ev(right, c);
+              case "+"          : return ev(left, c) +          ev(right, c);
+              case "*"          : return ev(left, c) *          ev(right, c);
+              case "/"          : return ev(left, c) /          ev(right, c);
+              case "%"          : return ev(left, c) %          ev(right, c);
+              case "-"          : return ev(left, c) -          ev(right, c);
+              case "<<"         : return ev(left, c) <<         ev(right, c);
+              case ">>"         : return ev(left, c) >>         ev(right, c);
+              case ">>>"        : return ev(left, c) >>>        ev(right, c);
+              case "=="         : return ev(left, c) ==         ev(right, c);
+              case "==="        : return ev(left, c) ===        ev(right, c);
+              case "!="         : return ev(left, c) !=         ev(right, c);
+              case "!=="        : return ev(left, c) !==        ev(right, c);
+              case "<"          : return ev(left, c) <          ev(right, c);
+              case "<="         : return ev(left, c) <=         ev(right, c);
+              case ">"          : return ev(left, c) >          ev(right, c);
+              case ">="         : return ev(left, c) >=         ev(right, c);
+              case "in"         : return ev(left, c) in         ev(right, c);
+              case "instanceof" : return ev(left, c) instanceof ev(right, c);
             }
             throw def;
         });
-        def(AST_Conditional, function(){
-            return ev(this.condition)
-                ? ev(this.consequent)
-                : ev(this.alternative);
+        def(AST_Conditional, function(compressor){
+            return ev(this.condition, compressor)
+                ? ev(this.consequent, compressor)
+                : ev(this.alternative, compressor);
         });
-        def(AST_SymbolRef, function(){
+        def(AST_SymbolRef, function(compressor){
             var d = this.definition();
-            if (d && d.constant && d.init) return ev(d.init);
+            if (d && d.constant && d.init) return ev(d.init, compressor);
             throw def;
         });
     })(function(node, func){
@@ -800,70 +798,78 @@ merge(Compressor.prototype, {
 
     // determine if expression has side effects
     (function(def){
-        def(AST_Node, function(){ return true });
+        def(AST_Node, function(compressor){ return true });
 
-        def(AST_EmptyStatement, function(){ return false });
-        def(AST_Constant, function(){ return false });
-        def(AST_This, function(){ return false });
+        def(AST_EmptyStatement, function(compressor){ return false });
+        def(AST_Constant, function(compressor){ return false });
+        def(AST_This, function(compressor){ return false });
 
-        def(AST_Block, function(){
+        def(AST_Call, function(compressor){
+            var pure = compressor.option("pure_funcs");
+            if (!pure) return true;
+            return pure.indexOf(this.expression.print_to_string()) < 0;
+        });
+
+        def(AST_Block, function(compressor){
             for (var i = this.body.length; --i >= 0;) {
-                if (this.body[i].has_side_effects())
+                if (this.body[i].has_side_effects(compressor))
                     return true;
             }
             return false;
         });
 
-        def(AST_SimpleStatement, function(){
-            return this.body.has_side_effects();
+        def(AST_SimpleStatement, function(compressor){
+            return this.body.has_side_effects(compressor);
         });
-        def(AST_Defun, function(){ return true });
-        def(AST_Function, function(){ return false });
-        def(AST_Binary, function(){
-            return this.left.has_side_effects()
-                || this.right.has_side_effects();
+        def(AST_Defun, function(compressor){ return true });
+        def(AST_Function, function(compressor){ return false });
+        def(AST_Binary, function(compressor){
+            return this.left.has_side_effects(compressor)
+                || this.right.has_side_effects(compressor);
         });
-        def(AST_Assign, function(){ return true });
-        def(AST_Conditional, function(){
-            return this.condition.has_side_effects()
-                || this.consequent.has_side_effects()
-                || this.alternative.has_side_effects();
+        def(AST_Assign, function(compressor){ return true });
+        def(AST_Conditional, function(compressor){
+            return this.condition.has_side_effects(compressor)
+                || this.consequent.has_side_effects(compressor)
+                || this.alternative.has_side_effects(compressor);
         });
-        def(AST_Unary, function(){
+        def(AST_Unary, function(compressor){
             return this.operator == "delete"
                 || this.operator == "++"
                 || this.operator == "--"
-                || this.expression.has_side_effects();
+                || this.expression.has_side_effects(compressor);
         });
-        def(AST_SymbolRef, function(){ return false });
-        def(AST_Object, function(){
+        def(AST_SymbolRef, function(compressor){ return false });
+        def(AST_Object, function(compressor){
             for (var i = this.properties.length; --i >= 0;)
-                if (this.properties[i].has_side_effects())
+                if (this.properties[i].has_side_effects(compressor))
                     return true;
             return false;
         });
-        def(AST_ObjectProperty, function(){
-            return this.value.has_side_effects();
+        def(AST_ObjectProperty, function(compressor){
+            return this.value.has_side_effects(compressor);
         });
-        def(AST_Array, function(){
+        def(AST_Array, function(compressor){
             for (var i = this.elements.length; --i >= 0;)
-                if (this.elements[i].has_side_effects())
+                if (this.elements[i].has_side_effects(compressor))
                     return true;
             return false;
         });
-        // def(AST_Dot, function(){
-        //     return this.expression.has_side_effects();
-        // });
-        // def(AST_Sub, function(){
-        //     return this.expression.has_side_effects()
-        //         || this.property.has_side_effects();
-        // });
-        def(AST_PropAccess, function(){
-            return true;
+        def(AST_Dot, function(compressor){
+            if (!compressor.option("pure_getters")) return true;
+            return this.expression.has_side_effects(compressor);
         });
-        def(AST_Seq, function(){
-            return this.car.has_side_effects()
-                || this.cdr.has_side_effects();
+        def(AST_Sub, function(compressor){
+            if (!compressor.option("pure_getters")) return true;
+            return this.expression.has_side_effects(compressor)
+                || this.property.has_side_effects(compressor);
+        });
+        def(AST_PropAccess, function(compressor){
+            return !compressor.option("pure_getters");
+        });
+        def(AST_Seq, function(compressor){
+            return this.car.has_side_effects(compressor)
+                || this.cdr.has_side_effects(compressor);
         });
     })(function(node, func){
         node.DEFMETHOD("has_side_effects", func);
@@ -947,7 +953,7 @@ merge(Compressor.prototype, {
                         node.definitions.forEach(function(def){
                             if (def.value) {
                                 initializations.add(def.name.name, def.value);
-                                if (def.value.has_side_effects()) {
+                                if (def.value.has_side_effects(compressor)) {
                                     def.value.walk(tw);
                                 }
                             }
@@ -1024,7 +1030,7 @@ merge(Compressor.prototype, {
                                 line : def.name.start.line,
                                 col  : def.name.start.col
                             };
-                            if (def.value && def.value.has_side_effects()) {
+                            if (def.value && def.value.has_side_effects(compressor)) {
                                 def._unused_side_effects = true;
                                 compressor.warn("Side effects in initialization of unused variable {name} [{file}:{line},{col}]", w);
                                 return true;
@@ -1078,18 +1084,23 @@ merge(Compressor.prototype, {
                         }
                         return node;
                     }
-                    if (node instanceof AST_For && node.init instanceof AST_BlockStatement) {
+                    if (node instanceof AST_For) {
                         descend(node, this);
-                        // certain combination of unused name + side effect leads to:
-                        //    https://github.com/mishoo/UglifyJS2/issues/44
-                        // that's an invalid AST.
-                        // We fix it at this stage by moving the `var` outside the `for`.
-                        var body = node.init.body.slice(0, -1);
-                        node.init = node.init.body.slice(-1)[0].body;
-                        body.push(node);
-                        return in_list ? MAP.splice(body) : make_node(AST_BlockStatement, node, {
-                            body: body
-                        });
+
+                        if (node.init instanceof AST_BlockStatement) {
+                            // certain combination of unused name + side effect leads to:
+                            //    https://github.com/mishoo/UglifyJS2/issues/44
+                            // that's an invalid AST.
+                            // We fix it at this stage by moving the `var` outside the `for`.
+
+                            var body = node.init.body.slice(0, -1);
+                            node.init = node.init.body.slice(-1)[0].body;
+                            body.push(node);
+
+                            return in_list ? MAP.splice(body) : make_node(AST_BlockStatement, node, {
+                                body: body
+                            });
+                        }
                     }
                     if (node instanceof AST_Scope && node !== self)
                         return node;
@@ -1226,7 +1237,7 @@ merge(Compressor.prototype, {
 
     OPT(AST_SimpleStatement, function(self, compressor){
         if (compressor.option("side_effects")) {
-            if (!self.body.has_side_effects()) {
+            if (!self.body.has_side_effects(compressor)) {
                 compressor.warn("Dropping side-effect-free statement [{file}:{line},{col}]", self.start);
                 return make_node(AST_EmptyStatement, self);
             }
@@ -1610,7 +1621,7 @@ merge(Compressor.prototype, {
                     if (self.args.length != 1) {
                         return make_node(AST_Array, self, {
                             elements: self.args
-                        });
+                        }).transform(compressor);
                     }
                     break;
                   case "Object":
@@ -1624,11 +1635,30 @@ merge(Compressor.prototype, {
                     if (self.args.length == 0) return make_node(AST_String, self, {
                         value: ""
                     });
-                    return make_node(AST_Binary, self, {
+                    if (self.args.length <= 1) return make_node(AST_Binary, self, {
                         left: self.args[0],
                         operator: "+",
                         right: make_node(AST_String, self, { value: "" })
+                    }).transform(compressor);
+                    break;
+                  case "Number":
+                    if (self.args.length == 0) return make_node(AST_Number, self, {
+                        value: 0
                     });
+                    if (self.args.length == 1) return make_node(AST_UnaryPrefix, self, {
+                        expression: self.args[0],
+                        operator: "+"
+                    }).transform(compressor);
+                  case "Boolean":
+                    if (self.args.length == 0) return make_node(AST_False, self);
+                    if (self.args.length == 1) return make_node(AST_UnaryPrefix, self, {
+                        expression: make_node(AST_UnaryPrefix, null, {
+                            expression: self.args[0],
+                            operator: "!"
+                        }),
+                        operator: "!"
+                    }).transform(compressor);
+                    break;
                   case "Function":
                     if (all(self.args, function(x){ return x instanceof AST_String })) {
                         // quite a corner-case, but we can handle it:
@@ -1644,7 +1674,17 @@ merge(Compressor.prototype, {
                             ast = ast.transform(comp);
                             ast.figure_out_scope();
                             ast.mangle_names();
-                            var fun = ast.body[0].body.expression;
+                            var fun;
+                            try {
+                                ast.walk(new TreeWalker(function(node){
+                                    if (node instanceof AST_Lambda) {
+                                        fun = node;
+                                        throw ast;
+                                    }
+                                }));
+                            } catch(ex) {
+                                if (ex !== ast) throw ex;
+                            };
                             var args = fun.argnames.map(function(arg, i){
                                 return make_node(AST_String, self.args[i], {
                                     value: arg.print_to_string()
@@ -1664,6 +1704,7 @@ merge(Compressor.prototype, {
                                 compressor.warn(ex.toString());
                             } else {
                                 console.log(ex);
+                                throw ex;
                             }
                         }
                     }
@@ -1677,15 +1718,62 @@ merge(Compressor.prototype, {
                     right: exp.expression
                 }).transform(compressor);
             }
+            else if (exp instanceof AST_Dot && exp.expression instanceof AST_Array && exp.property == "join") EXIT: {
+                var separator = self.args.length == 0 ? "," : self.args[0].evaluate(compressor)[1];
+                if (separator == null) break EXIT; // not a constant
+                var elements = exp.expression.elements.reduce(function(a, el){
+                    el = el.evaluate(compressor);
+                    if (a.length == 0 || el.length == 1) {
+                        a.push(el);
+                    } else {
+                        var last = a[a.length - 1];
+                        if (last.length == 2) {
+                            // it's a constant
+                            var val = "" + last[1] + separator + el[1];
+                            a[a.length - 1] = [ make_node_from_constant(compressor, val, last[0]), val ];
+                        } else {
+                            a.push(el);
+                        }
+                    }
+                    return a;
+                }, []);
+                if (elements.length == 0) return make_node(AST_String, self, { value: "" });
+                if (elements.length == 1) return elements[0][0];
+                if (separator == "") {
+                    var first;
+                    if (elements[0][0] instanceof AST_String
+                        || elements[1][0] instanceof AST_String) {
+                        first = elements.shift()[0];
+                    } else {
+                        first = make_node(AST_String, self, { value: "" });
+                    }
+                    return elements.reduce(function(prev, el){
+                        return make_node(AST_Binary, el[0], {
+                            operator : "+",
+                            left     : prev,
+                            right    : el[0],
+                        });
+                    }, first).transform(compressor);
+                }
+                // need this awkward cloning to not affect original element
+                // best_of will decide which one to get through.
+                var node = self.clone();
+                node.expression = node.expression.clone();
+                node.expression.expression = node.expression.expression.clone();
+                node.expression.expression.elements = elements.map(function(el){
+                    return el[0];
+                });
+                return best_of(self, node);
+            }
         }
         if (compressor.option("side_effects")) {
             if (self.expression instanceof AST_Function
                 && self.args.length == 0
-                && !AST_Block.prototype.has_side_effects.call(self.expression)) {
+                && !AST_Block.prototype.has_side_effects.call(self.expression, compressor)) {
                 return make_node(AST_Undefined, self).transform(compressor);
             }
         }
-        return self;
+        return self.evaluate(compressor)[0];
     });
 
     OPT(AST_New, function(self, compressor){
@@ -1708,7 +1796,7 @@ merge(Compressor.prototype, {
     OPT(AST_Seq, function(self, compressor){
         if (!compressor.option("side_effects"))
             return self;
-        if (!self.car.has_side_effects()) {
+        if (!self.car.has_side_effects(compressor)) {
             // we shouldn't compress (1,eval)(something) to
             // eval(something) because that changes the meaning of
             // eval (becomes lexical instead of global).
@@ -1723,12 +1811,12 @@ merge(Compressor.prototype, {
         }
         if (compressor.option("cascade")) {
             if (self.car instanceof AST_Assign
-                && !self.car.left.has_side_effects()
+                && !self.car.left.has_side_effects(compressor)
                 && self.car.left.equivalent_to(self.cdr)) {
                 return self.car;
             }
-            if (!self.car.has_side_effects()
-                && !self.cdr.has_side_effects()
+            if (!self.car.has_side_effects(compressor)
+                && !self.cdr.has_side_effects(compressor)
                 && self.car.equivalent_to(self.cdr)) {
                 return self.car;
             }
@@ -1778,6 +1866,14 @@ merge(Compressor.prototype, {
         return self.evaluate(compressor)[0];
     });
 
+    function has_side_effects_or_prop_access(node, compressor) {
+        var save_pure_getters = compressor.option("pure_getters");
+        compressor.options.pure_getters = false;
+        var ret = node.has_side_effects(compressor);
+        compressor.options.pure_getters = save_pure_getters;
+        return ret;
+    }
+
     AST_Binary.DEFMETHOD("lift_sequences", function(compressor){
         if (compressor.option("sequences")) {
             if (this.left instanceof AST_Seq) {
@@ -1789,8 +1885,8 @@ merge(Compressor.prototype, {
                 return seq;
             }
             if (this.right instanceof AST_Seq
-                && !(this.operator == "||" || this.operator == "&&")
-                && !this.left.has_side_effects()) {
+                && this instanceof AST_Assign
+                && !has_side_effects_or_prop_access(this.left, compressor)) {
                 var seq = this.right;
                 var x = seq.to_array();
                 this.right = x.pop();
@@ -1807,7 +1903,7 @@ merge(Compressor.prototype, {
     OPT(AST_Binary, function(self, compressor){
         var reverse = compressor.has_directive("use asm") ? noop
             : function(op, force) {
-                if (force || !(self.left.has_side_effects() || self.right.has_side_effects())) {
+                if (force || !(self.left.has_side_effects(compressor) || self.right.has_side_effects(compressor))) {
                     if (op) self.operator = op;
                     var tmp = self.left;
                     self.left = self.right;
@@ -1820,7 +1916,37 @@ merge(Compressor.prototype, {
                 // if right is a constant, whatever side effects the
                 // left side might have could not influence the
                 // result.  hence, force switch.
-                reverse(null, true);
+
+                if (!(self.left instanceof AST_Binary
+                      && PRECEDENCE[self.left.operator] >= PRECEDENCE[self.operator])) {
+                    reverse(null, true);
+                }
+            }
+            if (/^[!=]==?$/.test(self.operator)) {
+                if (self.left instanceof AST_SymbolRef && self.right instanceof AST_Conditional) {
+                    if (self.right.consequent instanceof AST_SymbolRef
+                        && self.right.consequent.definition() === self.left.definition()) {
+                        if (/^==/.test(self.operator)) return self.right.condition;
+                        if (/^!=/.test(self.operator)) return self.right.condition.negate(compressor);
+                    }
+                    if (self.right.alternative instanceof AST_SymbolRef
+                        && self.right.alternative.definition() === self.left.definition()) {
+                        if (/^==/.test(self.operator)) return self.right.condition.negate(compressor);
+                        if (/^!=/.test(self.operator)) return self.right.condition;
+                    }
+                }
+                if (self.right instanceof AST_SymbolRef && self.left instanceof AST_Conditional) {
+                    if (self.left.consequent instanceof AST_SymbolRef
+                        && self.left.consequent.definition() === self.right.definition()) {
+                        if (/^==/.test(self.operator)) return self.left.condition;
+                        if (/^!=/.test(self.operator)) return self.left.condition.negate(compressor);
+                    }
+                    if (self.left.alternative instanceof AST_SymbolRef
+                        && self.left.alternative.definition() === self.right.definition()) {
+                        if (/^==/.test(self.operator)) return self.left.condition.negate(compressor);
+                        if (/^!=/.test(self.operator)) return self.left.condition;
+                    }
+                }
             }
         }
         self = self.lift_sequences(compressor);
@@ -1887,11 +2013,6 @@ merge(Compressor.prototype, {
             }
             break;
         }
-        var exp = self.evaluate(compressor);
-        if (exp.length > 1) {
-            if (best_of(exp[0], self) !== self)
-                return exp[0];
-        }
         if (compressor.option("comparisons")) {
             if (!(compressor.parent() instanceof AST_Binary)
                 || compressor.parent() instanceof AST_Assign) {
@@ -1911,7 +2032,76 @@ merge(Compressor.prototype, {
             && self.left.operator == "+" && self.left.is_string(compressor)) {
             return self.left;
         }
-        return self;
+        if (compressor.option("evaluate")) {
+            if (self.operator == "+") {
+                if (self.left instanceof AST_Constant
+                    && self.right instanceof AST_Binary
+                    && self.right.operator == "+"
+                    && self.right.left instanceof AST_Constant
+                    && self.right.is_string(compressor)) {
+                    self = make_node(AST_Binary, self, {
+                        operator: "+",
+                        left: make_node(AST_String, null, {
+                            value: "" + self.left.getValue() + self.right.left.getValue(),
+                            start: self.left.start,
+                            end: self.right.left.end
+                        }),
+                        right: self.right.right
+                    });
+                }
+                if (self.right instanceof AST_Constant
+                    && self.left instanceof AST_Binary
+                    && self.left.operator == "+"
+                    && self.left.right instanceof AST_Constant
+                    && self.left.is_string(compressor)) {
+                    self = make_node(AST_Binary, self, {
+                        operator: "+",
+                        left: self.left.left,
+                        right: make_node(AST_String, null, {
+                            value: "" + self.left.right.getValue() + self.right.getValue(),
+                            start: self.left.right.start,
+                            end: self.right.end
+                        })
+                    });
+                }
+                if (self.left instanceof AST_Binary
+                    && self.left.operator == "+"
+                    && self.left.is_string(compressor)
+                    && self.left.right instanceof AST_Constant
+                    && self.right instanceof AST_Binary
+                    && self.right.operator == "+"
+                    && self.right.left instanceof AST_Constant
+                    && self.right.is_string(compressor)) {
+                    self = make_node(AST_Binary, self, {
+                        operator: "+",
+                        left: make_node(AST_Binary, self.left, {
+                            operator: "+",
+                            left: self.left.left,
+                            right: make_node(AST_String, null, {
+                                value: "" + self.left.right.getValue() + self.right.left.getValue(),
+                                start: self.left.right.start,
+                                end: self.right.left.end
+                            })
+                        }),
+                        right: self.right.right
+                    });
+                }
+            }
+        }
+        // x * (y * z)  ==>  x * y * z
+        if (self.right instanceof AST_Binary
+            && self.right.operator == self.operator
+            && (self.operator == "*" || self.operator == "&&" || self.operator == "||"))
+        {
+            self.left = make_node(AST_Binary, self.left, {
+                operator : self.operator,
+                left     : self.left,
+                right    : self.right.left
+            });
+            self.right = self.right.right;
+            return self.transform(compressor);
+        }
+        return self.evaluate(compressor)[0];
     });
 
     OPT(AST_SymbolRef, function(self, compressor){

lib/output.js

@@ -61,6 +61,7 @@ function OutputStream(options) {
         comments      : false,
         preserve_line : false,
         screw_ie8     : false,
+        preamble      : null,
     }, true);
 
     var indentation = 0;
@@ -299,6 +300,10 @@ function OutputStream(options) {
         return OUTPUT;
     };
 
+    if (options.preamble) {
+        print(options.preamble.replace(/\r\n?|[\n\u2028\u2029]|\s*$/g, "\n"));
+    }
+
     var stack = [];
     return {
         get             : get,
@@ -378,14 +383,15 @@ function OutputStream(options) {
             var start = self.start;
             if (start && !start._comments_dumped) {
                 start._comments_dumped = true;
-                var comments = start.comments_before;
+                var comments = start.comments_before || [];
 
                 // XXX: ugly fix for https://github.com/mishoo/UglifyJS2/issues/112
                 //      if this node is `return` or `throw`, we cannot allow comments before
                 //      the returned or thrown value.
-                if (self instanceof AST_Exit &&
-                    self.value && self.value.start.comments_before.length > 0) {
-                    comments = (comments || []).concat(self.value.start.comments_before);
+                if (self instanceof AST_Exit && self.value
+                    && self.value.start.comments_before
+                    && self.value.start.comments_before.length > 0) {
+                    comments = comments.concat(self.value.start.comments_before);
                     self.value.start.comments_before = [];
                 }
 
@@ -399,7 +405,7 @@ function OutputStream(options) {
                     });
                 }
                 comments.forEach(function(c){
-                    if (c.type == "comment1") {
+                    if (/comment[134]/.test(c.type)) {
                         output.print("//" + c.value + "\n");
                         output.indent();
                     }
@@ -475,11 +481,7 @@ function OutputStream(options) {
             var so = this.operator, sp = PRECEDENCE[so];
             if (pp > sp
                 || (pp == sp
-                    && this === p.right
-                    && !(so == po &&
-                         (so == "*" ||
-                          so == "&&" ||
-                          so == "||")))) {
+                    && this === p.right)) {
                 return true;
             }
         }
@@ -506,8 +508,17 @@ function OutputStream(options) {
     });
 
     PARENS(AST_Call, function(output){
-        var p = output.parent();
-        return p instanceof AST_New && p.expression === this;
+        var p = output.parent(), p1;
+        if (p instanceof AST_New && p.expression === this)
+            return true;
+
+        // workaround for Safari bug.
+        // https://bugs.webkit.org/show_bug.cgi?id=123506
+        return this.expression instanceof AST_Function
+            && p instanceof AST_PropAccess
+            && p.expression === this
+            && (p1 = output.parent(1)) instanceof AST_Assign
+            && p1.left === p;
     });
 
     PARENS(AST_New, function(output){
@@ -989,7 +1000,18 @@ function OutputStream(options) {
         self.left.print(output);
         output.space();
         output.print(self.operator);
-        output.space();
+        if (self.operator == "<"
+            && self.right instanceof AST_UnaryPrefix
+            && self.right.operator == "!"
+            && self.right.expression instanceof AST_UnaryPrefix
+            && self.right.expression.operator == "--") {
+            // space is mandatory to avoid outputting <!--
+            // http://javascript.spec.whatwg.org/#comment-syntax
+            output.print(" ");
+        } else {
+            // the space is optional depending on "beautify"
+            output.space();
+        }
         self.right.print(output);
     });
     DEFPRINT(AST_Conditional, function(self, output){
@@ -1053,10 +1075,14 @@ function OutputStream(options) {
     });
     DEFPRINT(AST_ObjectSetter, function(self, output){
         output.print("set");
+        output.space();
+        self.key.print(output);
         self.value._do_print(output, true);
     });
     DEFPRINT(AST_ObjectGetter, function(self, output){
         output.print("get");
+        output.space();
+        self.key.print(output);
         self.value._do_print(output, true);
     });
     DEFPRINT(AST_Symbol, function(self, output){

lib/parse.js

@@ -170,7 +170,7 @@ function is_identifier_char(ch) {
 function is_identifier_string(str){
     var i = str.length;
     if (i == 0) return false;
-    if (is_digit(str.charCodeAt(0))) return false;
+    if (!is_identifier_start(str.charCodeAt(0))) return false;
     while (--i >= 0) {
         if (!is_identifier_char(str.charAt(i)))
             return false;
@@ -210,7 +210,7 @@ function is_token(token, type, val) {
 
 var EX_EOF = {};
 
-function tokenizer($TEXT, filename) {
+function tokenizer($TEXT, filename, html5_comments) {
 
     var S = {
         text            : $TEXT.replace(/\r\n?|[\n\u2028\u2029]/g, "\n").replace(/\uFEFF/g, ''),
@@ -242,6 +242,14 @@ function tokenizer($TEXT, filename) {
         return ch;
     };
 
+    function forward(i) {
+        while (i-- > 0) next();
+    };
+
+    function looking_at(str) {
+        return S.text.substr(S.pos, str.length) == str;
+    };
+
     function find(what, signal_eof) {
         var pos = S.text.indexOf(what, S.pos);
         if (signal_eof && pos == -1) throw EX_EOF;
@@ -254,10 +262,12 @@ function tokenizer($TEXT, filename) {
         S.tokpos = S.pos;
     };
 
+    var prev_was_dot = false;
     function token(type, value, is_comment) {
         S.regex_allowed = ((type == "operator" && !UNARY_POSTFIX(value)) ||
                            (type == "keyword" && KEYWORDS_BEFORE_EXPRESSION(value)) ||
                            (type == "punc" && PUNC_BEFORE_EXPRESSION(value)));
+        prev_was_dot = (type == "punc" && value == ".");
         var ret = {
             type   : type,
             value  : value,
@@ -379,8 +389,8 @@ function tokenizer($TEXT, filename) {
         return token("string", ret);
     });
 
-    function read_line_comment() {
-        next();
+    function skip_line_comment(type) {
+        var regex_allowed = S.regex_allowed;
         var i = find("\n"), ret;
         if (i == -1) {
             ret = S.text.substr(S.pos);
@@ -389,11 +399,13 @@ function tokenizer($TEXT, filename) {
             ret = S.text.substring(S.pos, i);
             S.pos = i;
         }
-        return token("comment1", ret, true);
+        S.comments_before.push(token(type, ret, true));
+        S.regex_allowed = regex_allowed;
+        return next_token();
     };
 
-    var read_multiline_comment = with_eof_error("Unterminated multiline comment", function(){
-        next();
+    var skip_multiline_comment = with_eof_error("Unterminated multiline comment", function(){
+        var regex_allowed = S.regex_allowed;
         var i = find("*/", true);
         var text = S.text.substring(S.pos, i);
         var a = text.split("\n"), n = a.length;
@@ -403,8 +415,11 @@ function tokenizer($TEXT, filename) {
         if (n > 1) S.col = a[n - 1].length;
         else S.col += a[n - 1].length;
         S.col += 2;
-        S.newline_before = S.newline_before || text.indexOf("\n") >= 0;
-        return token("comment2", text, true);
+        var nlb = S.newline_before = S.newline_before || text.indexOf("\n") >= 0;
+        S.comments_before.push(token("comment2", text, true));
+        S.regex_allowed = regex_allowed;
+        S.newline_before = nlb;
+        return next_token();
     });
 
     function read_name() {
@@ -468,16 +483,13 @@ function tokenizer($TEXT, filename) {
 
     function handle_slash() {
         next();
-        var regex_allowed = S.regex_allowed;
         switch (peek()) {
           case "/":
-            S.comments_before.push(read_line_comment());
-            S.regex_allowed = regex_allowed;
-            return next_token();
+            next();
+            return skip_line_comment("comment1");
           case "*":
-            S.comments_before.push(read_multiline_comment());
-            S.regex_allowed = regex_allowed;
-            return next_token();
+            next();
+            return skip_multiline_comment();
         }
         return S.regex_allowed ? read_regexp("") : read_operator("/");
     };
@@ -491,6 +503,7 @@ function tokenizer($TEXT, filename) {
 
     function read_word() {
         var word = read_name();
+        if (prev_was_dot) return token("name", word);
         return KEYWORDS_ATOM(word) ? token("atom", word)
             : !KEYWORDS(word) ? token("name", word)
             : OPERATORS(word) ? token("operator", word)
@@ -513,6 +526,16 @@ function tokenizer($TEXT, filename) {
             return read_regexp(force_regexp);
         skip_whitespace();
         start_token();
+        if (html5_comments) {
+            if (looking_at("<!--")) {
+                forward(4);
+                return skip_line_comment("comment3");
+            }
+            if (looking_at("-->") && S.newline_before) {
+                forward(3);
+                return skip_line_comment("comment4");
+            }
+        }
         var ch = peek();
         if (!ch) return token("eof");
         var code = ch.charCodeAt(0);
@@ -556,10 +579,10 @@ var UNARY_POSTFIX = makePredicate([ "--", "++" ]);
 var ASSIGNMENT = makePredicate([ "=", "+=", "-=", "/=", "*=", "%=", ">>=", "<<=", ">>>=", "|=", "^=", "&=" ]);
 
 var PRECEDENCE = (function(a, ret){
-    for (var i = 0, n = 1; i < a.length; ++i, ++n) {
+    for (var i = 0; i < a.length; ++i) {
         var b = a[i];
         for (var j = 0; j < b.length; ++j) {
-            ret[b[j]] = n;
+            ret[b[j]] = i + 1;
         }
     }
     return ret;
@@ -588,14 +611,18 @@ var ATOMIC_START_TOKEN = array_to_hash([ "atom", "num", "string", "regexp", "nam
 function parse($TEXT, options) {
 
     options = defaults(options, {
-        strict     : false,
-        filename   : null,
-        toplevel   : null,
-        expression : false
+        strict         : false,
+        filename       : null,
+        toplevel       : null,
+        expression     : false,
+        html5_comments : true,
     });
 
     var S = {
-        input         : typeof $TEXT == "string" ? tokenizer($TEXT, options.filename) : $TEXT,
+        input         : (typeof $TEXT == "string"
+                         ? tokenizer($TEXT, options.filename,
+                                     options.html5_comments)
+                         : $TEXT),
         token         : null,
         prev          : null,
         peeked        : null,
@@ -688,12 +715,16 @@ function parse($TEXT, options) {
         };
     };
 
-    var statement = embed_tokens(function() {
-        var tmp;
+    function handle_regexp() {
         if (is("operator", "/") || is("operator", "/=")) {
             S.peeked = null;
             S.token = S.input(S.token.value.substr(1)); // force regexp
         }
+    };
+
+    var statement = embed_tokens(function() {
+        var tmp;
+        handle_regexp();
         switch (S.token.type) {
           case "string":
             var dir = S.in_directives, stat = simple_statement();
@@ -758,7 +789,7 @@ function parse($TEXT, options) {
                 return for_();
 
               case "function":
-                return function_(true);
+                return function_(AST_Defun);
 
               case "if":
                 return if_();
@@ -821,6 +852,18 @@ function parse($TEXT, options) {
         S.labels.push(label);
         var stat = statement();
         S.labels.pop();
+        if (!(stat instanceof AST_IterationStatement)) {
+            // check for `continue` that refers to this label.
+            // those should be reported as syntax errors.
+            // https://github.com/mishoo/UglifyJS2/issues/287
+            label.references.forEach(function(ref){
+                if (ref instanceof AST_Continue) {
+                    ref = ref.label.start;
+                    croak("Continue label `" + label.name + "` refers to non-IterationStatement.",
+                          ref.line, ref.col, ref.pos);
+                }
+            });
+        }
         return new AST_LabeledStatement({ body: stat, label: label });
     };
 
@@ -829,18 +872,22 @@ function parse($TEXT, options) {
     };
 
     function break_cont(type) {
-        var label = null;
+        var label = null, ldef;
         if (!can_insert_semicolon()) {
             label = as_symbol(AST_LabelRef, true);
         }
         if (label != null) {
-            if (!find_if(function(l){ return l.name == label.name }, S.labels))
+            ldef = find_if(function(l){ return l.name == label.name }, S.labels);
+            if (!ldef)
                 croak("Undefined label " + label.name);
+            label.thedef = ldef;
         }
         else if (S.in_loop == 0)
             croak(type.TYPE + " not inside a loop or switch");
         semicolon();
-        return new type({ label: label });
+        var stat = new type({ label: label });
+        if (ldef) ldef.references.push(stat);
+        return stat;
     };
 
     function for_() {
@@ -886,19 +933,12 @@ function parse($TEXT, options) {
         });
     };
 
-    var function_ = function(in_statement, ctor) {
-        var is_accessor = ctor === AST_Accessor;
-        var name = (is("name") ? as_symbol(in_statement
-                                           ? AST_SymbolDefun
-                                           : is_accessor
-                                           ? AST_SymbolAccessor
-                                           : AST_SymbolLambda)
-                    : is_accessor && (is("string") || is("num")) ? as_atom_node()
-                    : null);
+    var function_ = function(ctor) {
+        var in_statement = ctor === AST_Defun;
+        var name = is("name") ? as_symbol(in_statement ? AST_SymbolDefun : AST_SymbolLambda) : null;
         if (in_statement && !name)
             unexpected();
         expect("(");
-        if (!ctor) ctor = in_statement ? AST_Defun : AST_Function;
         return new ctor({
             name: name,
             argnames: (function(first, a){
@@ -1069,7 +1109,9 @@ function parse($TEXT, options) {
         var tok = S.token, ret;
         switch (tok.type) {
           case "name":
-            return as_symbol(AST_SymbolRef);
+          case "keyword":
+            ret = _make_symbol(AST_SymbolRef);
+            break;
           case "num":
             ret = new AST_Number({ start: tok, end: tok, value: tok.value });
             break;
@@ -1120,7 +1162,7 @@ function parse($TEXT, options) {
         }
         if (is("keyword", "function")) {
             next();
-            var func = function_(false);
+            var func = function_(AST_Function);
             func.start = start;
             func.end = prev();
             return subscripts(func, allow_calls);
@@ -1168,8 +1210,8 @@ function parse($TEXT, options) {
                 if (name == "get") {
                     a.push(new AST_ObjectGetter({
                         start : start,
-                        key   : name,
-                        value : function_(false, AST_Accessor),
+                        key   : as_atom_node(),
+                        value : function_(AST_Accessor),
                         end   : prev()
                     }));
                     continue;
@@ -1177,8 +1219,8 @@ function parse($TEXT, options) {
                 if (name == "set") {
                     a.push(new AST_ObjectSetter({
                         start : start,
-                        key   : name,
-                        value : function_(false, AST_Accessor),
+                        key   : as_atom_node(),
+                        value : function_(AST_Accessor),
                         end   : prev()
                     }));
                     continue;
@@ -1226,17 +1268,21 @@ function parse($TEXT, options) {
         }
     };
 
+    function _make_symbol(type) {
+        var name = S.token.value;
+        return new (name == "this" ? AST_This : type)({
+            name  : String(name),
+            start : S.token,
+            end   : S.token
+        });
+    };
+
     function as_symbol(type, noerror) {
         if (!is("name")) {
             if (!noerror) croak("Name expected");
             return null;
         }
-        var name = S.token.value;
-        var sym = new (name == "this" ? AST_This : type)({
-            name  : String(S.token.value),
-            start : S.token,
-            end   : S.token
-        });
+        var sym = _make_symbol(type);
         next();
         return sym;
     };
@@ -1279,6 +1325,7 @@ function parse($TEXT, options) {
         var start = S.token;
         if (is("operator") && UNARY_PREFIX(start.value)) {
             next();
+            handle_regexp();
             var ex = make_unary(AST_UnaryPrefix, start.value, maybe_unary(allow_calls));
             ex.start = start;
             ex.end = prev();

lib/scope.js

@@ -64,9 +64,9 @@ SymbolDef.prototype = {
     mangle: function(options) {
         if (!this.mangled_name && !this.unmangleable(options)) {
             var s = this.scope;
-            if (this.orig[0] instanceof AST_SymbolLambda && !options.screw_ie8)
+            if (!options.screw_ie8 && this.orig[0] instanceof AST_SymbolLambda)
                 s = s.parent_scope;
-            this.mangled_name = s.next_mangled(options);
+            this.mangled_name = s.next_mangled(options, this);
         }
     }
 };
@@ -82,18 +82,14 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(){
     // pass 1: setup scope chaining and handle definitions
     var self = this;
     var scope = self.parent_scope = null;
-    var labels = new Dictionary();
     var nesting = 0;
     var tw = new TreeWalker(function(node, descend){
         if (node instanceof AST_Scope) {
             node.init_scope_vars(nesting);
             var save_scope = node.parent_scope = scope;
-            var save_labels = labels;
             ++nesting;
             scope = node;
-            labels = new Dictionary();
             descend();
-            labels = save_labels;
             scope = save_scope;
             --nesting;
             return true;        // don't descend again in TreeWalker
@@ -108,22 +104,9 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(){
                 s.uses_with = true;
             return;
         }
-        if (node instanceof AST_LabeledStatement) {
-            var l = node.label;
-            if (labels.has(l.name))
-                throw new Error(string_template("Label {name} defined twice", l));
-            labels.set(l.name, l);
-            descend();
-            labels.del(l.name);
-            return true;        // no descend again
-        }
         if (node instanceof AST_Symbol) {
             node.scope = scope;
         }
-        if (node instanceof AST_Label) {
-            node.thedef = node;
-            node.init_scope_vars();
-        }
         if (node instanceof AST_SymbolLambda) {
             scope.def_function(node);
         }
@@ -150,15 +133,6 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(){
             // identifier in the enclosing scope)
             scope.def_variable(node);
         }
-        if (node instanceof AST_LabelRef) {
-            var sym = labels.get(node.name);
-            if (!sym) throw new Error(string_template("Undefined label {name} [{line},{col}]", {
-                name: node.name,
-                line: node.start.line,
-                col: node.start.col
-            }));
-            node.thedef = sym;
-        }
     });
     self.walk(tw);
 
@@ -173,10 +147,6 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(){
             func = prev_func;
             return true;
         }
-        if (node instanceof AST_LabelRef) {
-            node.reference();
-            return true;
-        }
         if (node instanceof AST_SymbolRef) {
             var name = node.name;
             var sym = node.scope.find_variable(name);
@@ -195,7 +165,7 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(){
                     for (var s = node.scope; s && !s.uses_eval; s = s.parent_scope)
                         s.uses_eval = true;
                 }
-                if (name == "arguments") {
+                if (func && name == "arguments") {
                     func.uses_arguments = true;
                 }
             } else {
@@ -241,14 +211,6 @@ AST_SymbolRef.DEFMETHOD("reference", function() {
     this.frame = this.scope.nesting - def.scope.nesting;
 });
 
-AST_Label.DEFMETHOD("init_scope_vars", function(){
-    this.references = [];
-});
-
-AST_LabelRef.DEFMETHOD("reference", function(){
-    this.thedef.references.push(this);
-});
-
 AST_Scope.DEFMETHOD("find_variable", function(name){
     if (name instanceof AST_Symbol) name = name.name;
     return this.variables.get(name)
@@ -294,6 +256,19 @@ AST_Scope.DEFMETHOD("next_mangled", function(options){
     }
 });
 
+AST_Function.DEFMETHOD("next_mangled", function(options, def){
+    // #179, #326
+    // in Safari strict mode, something like (function x(x){...}) is a syntax error;
+    // a function expression's argument cannot shadow the function expression's name
+
+    var tricky_def = def.orig[0] instanceof AST_SymbolFunarg && this.name && this.name.definition();
+    while (true) {
+        var name = AST_Lambda.prototype.next_mangled.call(this, options, def);
+        if (!(tricky_def && tricky_def.mangled_name == name))
+            return name;
+    }
+});
+
 AST_Scope.DEFMETHOD("references", function(sym){
     if (sym instanceof AST_Symbol) sym = sym.definition();
     return this.enclosed.indexOf(sym) < 0 ? null : sym;

lib/utils.js

@@ -86,12 +86,16 @@ function DefaultsError(msg, defs) {
     this.defs = defs;
 };
 
+DefaultsError.croak = function(msg, defs) {
+    throw new DefaultsError(msg, defs);
+};
+
 function defaults(args, defs, croak) {
     if (args === true)
         args = {};
     var ret = args || {};
     if (croak) for (var i in ret) if (ret.hasOwnProperty(i) && !defs.hasOwnProperty(i))
-        throw new DefaultsError("`" + i + "` is not a supported option", defs);
+        DefaultsError.croak("`" + i + "` is not a supported option", defs);
     for (var i in defs) if (defs.hasOwnProperty(i)) {
         ret[i] = (args && args.hasOwnProperty(i)) ? args[i] : defs[i];
     }

package.json

@@ -3,7 +3,7 @@
     "description": "JavaScript parser, mangler/compressor and beautifier toolkit",
     "homepage": "http://lisperator.net/uglifyjs",
     "main": "tools/node.js",
-    "version": "2.4.0",
+    "version": "2.4.5",
     "engines": { "node" : ">=0.4.0" },
     "maintainers": [{
         "name": "Mihai Bazon",

test/compress/arrays.js

@@ -12,3 +12,63 @@ holes_and_undefined: {
         z=[1,void 0,3];
     }
 }
+
+constant_join: {
+    options = {
+        unsafe   : true,
+        evaluate : true
+    };
+    input: {
+        var a = [ "foo", "bar", "baz" ].join("");
+        var a1 = [ "foo", "bar", "baz" ].join();
+        var b = [ "foo", 1, 2, 3, "bar" ].join("");
+        var c = [ boo(), "foo", 1, 2, 3, "bar", bar() ].join("");
+        var c1 = [ boo(), bar(), "foo", 1, 2, 3, "bar", bar() ].join("");
+        var c2 = [ 1, 2, "foo", "bar", baz() ].join("");
+        var d = [ "foo", 1 + 2 + "bar", "baz" ].join("-");
+        var e = [].join(foo + bar);
+        var f = [].join("");
+        var g = [].join("foo");
+    }
+    expect: {
+        var a = "foobarbaz";
+        var a1 = "foo,bar,baz";
+        var b = "foo123bar";
+        var c = boo() + "foo123bar" + bar();
+        var c1 = "" + boo() + bar() + "foo123bar" + bar();
+        var c2 = "12foobar" + baz();
+        var d = "foo-3bar-baz";
+        var e = [].join(foo + bar);
+        var f = "";
+        var g = "";
+    }
+}
+
+constant_join_2: {
+    options = {
+        unsafe   : true,
+        evaluate : true
+    };
+    input: {
+        var a = [ "foo", "bar", boo(), "baz", "x", "y" ].join("");
+        var b = [ "foo", "bar", boo(), "baz", "x", "y" ].join("-");
+        var c = [ "foo", "bar", boo(), "baz", "x", "y" ].join("really-long-separator");
+        var d = [ "foo", "bar", boo(),
+                  [ "foo", 1, 2, 3, "bar" ].join("+"),
+                  "baz", "x", "y" ].join("-");
+        var e = [ "foo", "bar", boo(),
+                  [ "foo", 1, 2, 3, "bar" ].join("+"),
+                  "baz", "x", "y" ].join("really-long-separator");
+        var f = [ "str", "str" + variable, "foo", "bar", "moo" + foo ].join("");
+    }
+    expect: {
+        var a = "foobar" + boo() + "bazxy";
+        var b = [ "foo-bar", boo(), "baz-x-y" ].join("-");
+        var c = [ "foo", "bar", boo(), "baz", "x", "y" ].join("really-long-separator");
+        var d = [ "foo-bar", boo(), "foo+1+2+3+bar-baz-x-y" ].join("-");
+        var e = [ "foo", "bar", boo(),
+                  "foo+1+2+3+bar",
+                  "baz", "x", "y" ].join("really-long-separator");
+        var f = "strstr" + variable + "foobarmoo" + foo;
+    }
+}

test/compress/concat-strings.js

@@ -0,0 +1,22 @@
+concat_1: {
+    options = {
+        evaluate: true
+    };
+    input: {
+        var a = "foo" + "bar" + x() + "moo" + "foo" + y() + "x" + "y" + "z" + q();
+        var b = "foo" + 1 + x() + 2 + "boo";
+        var c = 1 + x() + 2 + "boo";
+
+        // this CAN'T safely be shortened to 1 + x() + "5boo"
+        var d = 1 + x() + 2 + 3 + "boo";
+
+        var e = 1 + x() + 2 + "X" + 3 + "boo";
+    }
+    expect: {
+        var a = "foobar" + x() + "moofoo" + y() + "xyz" + q();
+        var b = "foo1" + x() + "2boo";
+        var c = 1 + x() + 2 + "boo";
+        var d = 1 + x() + 2 + 3 + "boo";
+        var e = 1 + x() + 2 + "X3boo";
+    }
+}

test/compress/issue-126.js

@@ -0,0 +1,24 @@
+concatenate_rhs_strings: {
+    options = {
+        evaluate: true,
+        unsafe: true,
+    }
+    input: {
+        foo(bar() + 123 + "Hello" + "World");
+        foo(bar() + (123 + "Hello") + "World");
+        foo((bar() + 123) + "Hello" + "World");
+        foo(bar() + 123 + "Hello" + "World" + ("Foo" + "Bar"));
+        foo("Foo" + "Bar" + bar() + 123 + "Hello" + "World" + ("Foo" + "Bar"));
+        foo("Hello" + bar() + 123 + "World");
+        foo(bar() + 'Foo' + (10 + parseInt('10')));
+    }
+    expect: {
+        foo(bar() + 123 + "HelloWorld");
+        foo(bar() + "123HelloWorld");
+        foo((bar() + 123) + "HelloWorld");
+        foo(bar() + 123 + "HelloWorldFooBar");
+        foo("FooBar" + bar() + "123HelloWorldFooBar");
+        foo("Hello" + bar() + "123World");
+        foo(bar() + 'Foo' + (10 + parseInt('10')));
+    }
+}

test/compress/issue-267.js

@@ -0,0 +1,11 @@
+issue_267: {
+    options = { comparisons: true };
+    input: {
+        x = a % b / b * c * 2;
+        x = a % b * 2
+    }
+    expect: {
+        x = a % b / b * c * 2;
+        x = a % b * 2;
+    }
+}

test/compress/issue-269.js

@@ -0,0 +1,66 @@
+issue_269_1: {
+	options = {unsafe: true};
+	input: {
+		f(
+			String(x),
+			Number(x),
+			Boolean(x),
+
+			String(),
+			Number(),
+			Boolean()
+		);
+	}
+	expect: {
+		f(
+			x + '', +x, !!x,
+			'', 0, false
+		);
+	}
+}
+
+issue_269_dangers: {
+	options = {unsafe: true};
+	input: {
+		f(
+			String(x, x),
+			Number(x, x),
+			Boolean(x, x)
+		);
+	}
+	expect: {
+		f(String(x, x), Number(x, x), Boolean(x, x));
+	}
+}
+
+issue_269_in_scope: {
+	options = {unsafe: true};
+	input: {
+		var String, Number, Boolean;
+		f(
+			String(x),
+			Number(x, x),
+			Boolean(x)
+		);
+	}
+	expect: {
+		var String, Number, Boolean;
+		f(String(x), Number(x, x), Boolean(x));
+	}
+}
+
+strings_concat: {
+	options = {unsafe: true};
+	input: {
+		f(
+			String(x + 'str'),
+			String('str' + x)
+		);
+	}
+	expect: {
+		f(
+			x + 'str',
+			'str' + x
+		);
+	}
+}

test/compress/sequences.js

@@ -101,10 +101,12 @@ lift_sequences_1: {
 lift_sequences_2: {
     options = { sequences: true, evaluate: true };
     input: {
-        q = 1 + (foo(), bar(), 5) + 7 * (5 / (3 - (a(), (QW=ER), c(), 2))) - (x(), y(), 5);
+        foo.x = (foo = {}, 10);
+        bar = (bar = {}, 10);
     }
     expect: {
-        foo(), bar(), a(), QW = ER, c(), x(), y(), q = 36
+        foo.x = (foo = {}, 10),
+        bar = {}, bar = 10;
     }
 }
 

test/run-tests.js

@@ -7,8 +7,15 @@ var assert = require("assert");
 var sys = require("util");
 
 var tests_dir = path.dirname(module.filename);
+var failures = 0;
+var failed_files = {};
 
 run_compress_tests();
+if (failures) {
+    sys.error("\n!!! Failed " + failures + " test cases.");
+    sys.error("!!! " + Object.keys(failed_files).join(", "));
+    process.exit(1);
+}
 
 /* -----[ utils ]----- */
 
@@ -83,6 +90,8 @@ function run_compress_tests() {
                     output: output,
                     expected: expect
                 });
+                failures++;
+                failed_files[file] = 1;
             }
         }
         var tests = parse_test(path.resolve(dir, file));