您可以使用 ECMAScript 6 的 String.prototype.startsWith() 方法，但它是 尚未在所有浏览器中支持.您需要使用 shim/polyfill 将其添加到不支持它的浏览器上.创建一个符合 所有细节的实现规范 有点复杂.如果您想要一个忠实的垫片，请使用:

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 的 String.prototype.startsWith 垫片，或
• es6-shim，它尽可能多地填充 ES6 规范，包括 String.prototype.startsWith.

• 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.

一旦你对方法进行了填充(或者如果你只支持已经拥有它的浏览器和 JavaScript 引擎)，你可以像这样使用它:

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