String.prototype.includes = function (string, index) {
	return this.indexOf(string, index) !== -1;
};

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;
};

Add explicit exception required by the spec