Object.prototype.isPrototypeOf()

Why Object.prototype.isPrototypeOf ?

The isPrototypeOf () method checks whether an object exists in another object hierarchy. This returns boolean values. If true returns, that object is in control of the specified object. If False returns, that object is not in control of the specified object.

object.isPrototypeOf( obj )

• obj:The object prototype to be checked against Object.
• object: The object chain to be checked in for the prototype.

returns:

• true if object is the prototype of o; false if o is not an object or if object is not the prototype of o.

---

JavaScript Object.prototype.isPrototypeOf Examples

Example 1

        function myObject1() { }
        function myObject2() { }

        myObject1.prototype = Object.create(myObject2.prototype);

        let myObject3 = new myObject1();
        console.log(myObject1.prototype.isPrototypeOf(myObject3));
        console.log(myObject2.prototype.isPrototypeOf(myObject3));

output:

true
true

---

Example 2

        function per1() { };
        function per2() { };
        function per3() { };

        per1.prototype = Object.create(per2.prototype);
        per2.prototype = Object.create(per1.prototype);
        var MyObject = new per3();

        console.log(per3.prototype.isPrototypeOf(per3));
        console.log(per1.prototype.isPrototypeOf(per3));
        console.log(per2.prototype.isPrototypeOf(per3));
        console.log(Object.prototype.isPrototypeOf(per1));

output:

false
false
false
true

---

Sources:

• https://developer.mozilla.org
• https://www.oreilly.com

---

Browser Support

Chrome	yes
Edge	yes
Firefox	1
Internet Explorer	yes
Opera	yes
Safari	yes
Android webview	yes
Chrome for Android	yes
Edge mobile	yes
Firefox for Android	4
Opera Android	yes