A small thing: If you are targeting Chrome, or modern browsers in general, use Object.defineProperty(Object.prototype, 'grep', { enumerable: false, v

A small thing: If you are targeting Chrome, or modern browsers in general, use Object.defineProperty(Object.prototype, 'grep', { enumerable: false, value: /* ... */ }); rather than Object.prototype.grep = /* ... */ This way, your 'grep' does not pollute for () loops.