ES6 String.prototype.startsWith polyfill

A robust & optimized ES3-compatible polyfill for the String.prototype.startsWith method in ECMAScript 6.

Other polyfills for String.prototype.startsWith are available:

• https://github.com/paulmillr/es6-shim/blob/d8c4ec246a15e7df55da60b7f9b745af84ca9021/es6-shim.js#L166-L173 by Paul Miller (fails some tests: 1, 2 passes all tests)
• https://github.com/google/traceur-compiler/blob/315bdad05d41de46d25337422d66686d63100d7a/src/runtime/polyfills/String.js#L19-L37 by Google (fails a lot of tests now uses this polyfill and passes all tests)

Installation

In a browser:

<script src="startswith.js"></script>

Via npm:

npm install string.prototype.startswith

Then, in Node.js:

require('string.prototype.startswith');

// On Windows and on Mac systems with default settings, case doesn’t matter,
// which allows you to do this instead:
require('String.prototype.startsWith');

Notes

Polyfills + test suites for String.prototype.endsWith and String.prototype.contains are available, too.

Author

Mathias Bynens

License

This polyfill is available under the MIT license.