startsWith

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if (!String.prototype.startsWith) {   Object.defineProperty(String.prototype, 'startsWith', {     enumerable: false,     configurable: false,     writable: false,     value: function (searchString, position) {       position = position || 0;       return this.indexOf(searchString, position) === position;     }   }); }//大拿拿了一个这样的代码出来，你妈，，吓死我了，，这不科学啊而且  this.indexOf(searchString, position) === position;这句感觉有问题