Constant caching

[fabiosantoscode]

Could we cache constants? Some strings (such as 'undefined', 'function', etc.), undefined, null, true, false, are used a lot! In unsafe mode, we could even cache Array.prototype, Object.prototype, [].slice (as in [].slice.call(arguments)). Large numbers may also be worth it to cache.

Declaring more safely cacheable things (such as window, document, document.documentElement, console, navigator) through an option could help us cache a ton of things.

[nickkolok]

It is said that gzip does it better and uglifier shouldn't do his work.

[fabiosantoscode]

You might be right, but if gzip could take all he load for this, we wouldn't even shorten true and false to !0 and !1.

If I recall correctly, jquery caches some strings and undefined. I don't think they would do it if it didn't bring anything to the table after gzip.

[nickkolok]

Even gzipped, file with !0 instead of true is ~2 bytes shorter - it depends on Haffman 's results.

I'm not sure, but I think that jQuery caches this variables - not strings! - not for shortening, but for safety. undefined, window and document can be redefined, so jQuery caches them into it's closure to avoid such errors.