function C(){} // defining a constructor function D(){} // defining another constructor var o = new C(); o instanceof C; // true, because: Object.getPrototypeOf(o) === C.prototype o instanceof D; // false, because D.prototype is nowhere in o's prototype chain o instanceof Object; // true, because: C.prototype instanceof Object // true C.prototype = {}; var o2 = new C(); o2 instanceof C; // true o instanceof C; // false, because C.prototype is nowhere in o's prototype chain anymore D.prototype = new C(); // use inheritance var o3 = new D(); o3 instanceof D; // true o3 instanceof C; // true var myString = new String(); var myDate = new Date(); myString instanceof String; // returns true myString instanceof Object; // returns true myString instanceof Date; // returns false myDate instanceof Date; // returns true myDate instanceof Object; // returns true myDate instanceof String; // returns false function Car(make, model, year) { this.make = make; this.model = model; this.year = year; } var mycar = new Car("Honda", "Accord", 1998); var a = mycar instanceof Car; // returns true var b = mycar instanceof Object; // returns true
总结
以上所述是小编给大家介绍的JavaScript中typeof与instanceof用法 ，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对脚本之家网站的支持！
您可能感兴趣的文章: