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enable typeof "undefined" for general use

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move out of unsafe, guard corner case with screw_id8 instead

closes #1446
This commit is contained in:
alexlamsl
2017-02-18 19:01:42 +08:00
parent fa668a28b4
commit e5badb9541
3 changed files with 77 additions and 30 deletions
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11
lib/compress.js
View File

@@ -2504,14 +2504,15 @@ merge(Compressor.prototype, {
// XXX: intentionally falling down to the next case
case "==":
case "!=":
// "undefined" == typeof x => undefined === x
if (self.left instanceof AST_String
&& self.left.value == "undefined"
&& self.right instanceof AST_UnaryPrefix
&& self.right.operator == "typeof"
&& compressor.option("unsafe")) {
if (!(self.right.expression instanceof AST_SymbolRef)
|| !self.right.expression.undeclared()) {
self.right = self.right.expression;
&& self.right.operator == "typeof") {
var expr = self.right.expression;
if (expr instanceof AST_SymbolRef ? !expr.undeclared()
: !(expr instanceof AST_PropAccess) || compressor.option("screw_ie8")) {
self.right = expr;
self.left = make_node(AST_Undefined, self.left).optimize(compressor);
if (self.operator.length == 2) self.operator += "=";
}

25
test/compress/issue-105.js
View File

@@ -1,25 +0,0 @@
typeof_eq_undefined: {
options = {
comparisons: true
};
input: { a = typeof b.c != "undefined" }
expect: { a = "undefined" != typeof b.c }
}
typeof_eq_undefined_unsafe: {
options = {
comparisons: true,
unsafe: true
};
input: { a = typeof b.c != "undefined" }
expect: { a = void 0 !== b.c }
}
typeof_eq_undefined_unsafe2: {
options = {
comparisons: true,
unsafe: true
};
input: { a = "undefined" != typeof b.c }
expect: { a = void 0 !== b.c }
}

71
test/compress/issue-1446.js Normal file
View File

@@ -0,0 +1,71 @@
typeof_eq_undefined: {
options = {
comparisons: true
}
input: {
var a = typeof b != "undefined";
b = typeof a != "undefined";
var c = typeof d.e !== "undefined";
var f = "undefined" === typeof g;
g = "undefined" === typeof f;
var h = "undefined" == typeof i.j;
}
expect: {
var a = "undefined" != typeof b;
b = void 0 !== a;
var c = void 0 !== d.e;
var f = "undefined" == typeof g;
g = void 0 === f;
var h = void 0 === i.j;
}
}
typeof_eq_undefined_ie8: {
options = {
comparisons: true,
screw_ie8: false
}
input: {
var a = typeof b != "undefined";
b = typeof a != "undefined";
var c = typeof d.e !== "undefined";
var f = "undefined" === typeof g;
g = "undefined" === typeof f;
var h = "undefined" == typeof i.j;
}
expect: {
var a = "undefined" != typeof b;
b = void 0 !== a;
var c = "undefined" != typeof d.e;
var f = "undefined" == typeof g;
g = void 0 === f;
var h = "undefined" == typeof i.j;
}
}
undefined_redefined: {
options = {
comparisons: true
}
input: {
function f(undefined) {
var n = 1;
return typeof n == "undefined";
}
}
expect_exact: "function f(undefined){var n=1;return void 0===n}"
}
undefined_redefined_mangle: {
options = {
comparisons: true
}
mangle = {}
input: {
function f(undefined) {
var n = 1;
return typeof n == "undefined";
}
}
expect_exact: "function f(n){var r=1;return void 0===r}"
}