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improve evaluate on typeof (#2550)

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- gated through `typeofs`
This commit is contained in:
Alex Lam S.L
2017-12-02 02:18:33 +08:00
committed by GitHub
parent 9a6b11f8e6
commit 8da3754e51
2 changed files with 86 additions and 4 deletions
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10
lib/compress.js
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@@ -1828,12 +1828,17 @@ merge(Compressor.prototype, {
return this;
});
def(AST_UnaryPrefix, function(compressor){
var e = this.expression;
// Function would be evaluated to an array and so typeof would
// incorrectly return 'object'. Hence making is a special case.
if (this.operator == "typeof" && this.expression instanceof AST_Function) {
if (compressor.option("typeofs")
&& this.operator == "typeof"
&& (e instanceof AST_Lambda
|| e instanceof AST_SymbolRef
&& e.fixed_value() instanceof AST_Lambda)) {
return typeof function(){};
}
var e = ev(this.expression, compressor);
e = ev(e, compressor);
if (e === this.expression) return this;
switch (this.operator) {
case "!": return !e;
@@ -1894,7 +1899,6 @@ merge(Compressor.prototype, {
return value === node ? this : value;
});
def(AST_SymbolRef, function(compressor){
if (!compressor.option("reduce_vars")) return this;
var fixed = this.fixed_value();
if (!fixed) return this;
this._eval = return_this;