Augment.js is a library that brings JavaScript 1.8.5 to any browser. It does this by augmenting built in types like Array and Object.
It combines the code snippets supplied by Mozilla for implementing methods using the exact algorithms specified in ECMA specifications.
For documentation and usage see the Augment.js docs site.
Thanks to Mozilla for doing most of the hard work by sharing pure JavaScript implementations for these methods on their website.