In summary, some Mozilla JS extensions from Firefox 3.0 have been adopted into ECMAScript. Some ECMAScript 5 APIs have been added to Firefox 3.5, but not all of them. All the browser vendors have put a lot of effort into ECMAScript 5, so I'd expect they're willing to actually implement it, too.
In summary, some Mozilla JS extensions from Firefox 3.0 have been adopted into ECMAScript. Some ECMAScript 5 APIs have been added to Firefox 3.5, but not all of them. All the browser vendors have put a lot of effort into ECMAScript 5, so I'd expect they're willing to actually implement it, too.