//to create an instance method on a js class
class nameOfClass {}
nameOfClass.prototype.nameOfInstanceMethod = function (){}
// now the class 'nameOfClass' has a property called nameOfInstanceMethod inside it's prototype chain
console.dir(nameOfClass) //to view it inside the prototype chain
var instanceOfOperator = nameOfObject instanceof typeOfObject;
var instanceOfOperator = nameOfObject instanceof typeOfObject;