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