You can use ECMAScript 6’s String.prototype.startsWith()
method, but it’s not yet supported in all browsers. You’ll want to use a shim/polyfill to add it on browsers that don’t support it. Creating an implementation that complies with all the details laid out in the spec is a little complicated. If you want a faithful shim, use either:
- Matthias Bynens’s
String.prototype.startsWith
shim, or - The es6-shim, which shims as much of the ES6 spec as possible, including
String.prototype.startsWith
.
Once you’ve shimmed the method (or if you’re only supporting browsers and JavaScript engines that already have it), you can use it like this:
console.log("Hello World!".startsWith("He")); // true
var haystack = "Hello world";
var prefix = 'orl';
console.log(haystack.startsWith(prefix)); // false