instanceOf 用于检查对象是否是某个构造函数(类型)的实例

<script>
 
    var arr = [1,2,3];
    console.log(arr instanceof Array);      //true
    console.log(Array instanceof Object);   //true
    console.log(arr instanceof Object);     //true
 
    //instanceOf在判断的时候,算上整条原型链
    //arr 是Array 和Object 任何一个类的示例
 
</script>

isProtoTypeOf 判断是否是某个实例对象的原型对象

<script>
 
    function Person() {
    }
    function Dog() {
    }
 
    Person.prototype.name = "嘿嘿";
    var p1 = new Person();
 
    console.log(Person.prototype.isPrototypeOf(p1));    //rue
    console.log(Object.prototype.isPrototypeOf(p1));    //true
    console.log(Dog.prototype.isPrototypeOf(p1));       //false
 
</script>