V8caching是否自动编译正则expression式？
所以我知道在JavaScript中实例化一个正则expression式会导致它被自动编译，如果这个正则expression式存储在一个variables中，它将被重用而不用重新编译。 例：
var re = /[Ff]oo|[Bb]ar/; "Foo".match(re); // ["Foo"] "Baz".match(re); // null 但是，重新编译的正则expression式是重复的还是V8（Chrome / Node.js）智能地重新使用它们（就像PHP与preg_ *函数一样）？
function isFooBar(str) { return str.match(/[Ff]oo|[Bb]ar/); } isFooBar("Foo"); // ["Foo"] isFooBar("Baz"); // null
所以为了澄清，我知道第一个例子导致了正则expression式的汇编。 但是第二个例子呢？
那么，让我们来看看。
// http://stackoverflow.com/questions/3466850/complex-password-regular-expression function isFooBar(str) { return 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} console.time('1');isFooBar("Foo");console.timeEnd('1'); console.time('2');isFooBar("Bar");console.timeEnd('2');
http://code.google.com/p/v8/issues/detail?id=933#c3
在Chrome 9中，我们已经移除了RegExp结果的原始caching。 这意味着我们不再需要一次又一次地在同一个input上重复同样的操作。 最初添加caching是为了说明过于简单（当时包括我们自己）在内的基准，通过添加这种caching（这在现实世界的场景中没有什么区别）太容易“游戏”了。 大多数的基准testing已经得到了很大的改进，所以我们决定删除caching（以及不可避免的开销）。 该caching已添加到v8修订版4083（在Chrome 5中发布）中，并在修订版5755中删除（将在Chrome 9中）