Firefox 18+ supports String#startsWith, String#endsWith
Thanks for writing this.
This prevents us from clobbering the native version, but we should go further and make our existing startsWith and endsWith true polyfills. If you feel like it, can you make our existing versions support the extra position argument as documented here and here?
If you don't feel like it, I'm happy to work on it myself when I get the time.
Yes, I'll make it.
Optional position argument
Documented new arguments and examples.
Updated unit tests
Firefox has also String#contains, which is similar to Prototype's String#include.
Review and pull, please. I've checked unit tests on Firefox 18.0.1 (with native implementation) and Chrome 24 (with our polyfill).
Should also be noted that Prototype's startsWith and endsWith does not align with ES6. It's missing support for the position argument.
NM, I see edge has added support for position but isn't totally accurate around resolving the position.