Every object gets the isPrototypeOf() method. Using this method we can find if the specific object is used as a prototype of another object.
Create a simple object monkey.
var monkey = { hair: true, feeds: 'bananas', breathes: 'air' };
Create a Human() constructor function and set its prototype property to point to monkey.
function Human(name) { this.name = name; } Human.prototype = monkey;
Now create a new Human object called george and check if monkey is prototype of george. It will return true.
var george = new Human('George'); monkey.isPrototypeOf(george) true