if (!String.prototype.startsWith) {

String.prototype.startsWith = function(string) {

let index = arguments.length < 2 ? 0 : arguments[1];

return this.slice(index).indexOf(string) === 0;

};

}

if (!String.prototype.endsWith) {

String.prototype.endsWith = function(string) {

let index = arguments.length < 2 ? this.length : arguments[1];

let foundIndex = this.lastIndexOf(string);

return foundIndex !== -1 && foundIndex === index - string.length;

};

}

if (!String.prototype.includes) {

String.prototype.includes = function(string, index) {

if (typeof string === 'object' && string instanceof RegExp) throw new TypeError("First argument to String.prototype.includes must not be a regular expression");

return this.indexOf(string, index) !== -1;

};

}