prototype-chain.js

/**
 * linking prototype objects to build a prototype chain
 * __proto__ vs Object.getPrototypeOf(obj) & Object.setPrototypeOf(obj)
 */

// 1.  obj --> otherProto.prototype  --> Object.prototype --> null
let otherProto = function() {
  this.prop1 = 456; // this means the instance of the object we are creating
  this.inner = function() {
    console.log("inner method on instance");
  };
  //automatically returns the instance of the object
};
otherProto.prototype.someMethod = function() {
  console.log("this is otherProto");
};
let obj = new otherProto();
// console.log(obj.prop1); // 456
// obj.inner();
// obj.someMethod();
// obj.toString();
// obj.__proto__.inner(); // fail
// Object.getPrototypeOf(obj).inner(); // fail
// Object.getPrototypeOf(obj).someMethod(); //yes

// 2.protoObj --> Object.prototype --> null
let protoObj = {
  prop1: 456,
  someMethod: function() {
    console.log("this is someMethod");
  }
}; // let protoObj = new Object();  protoObj.prop1 = 456; protoObj.someMethod = function(){}
//Object.getPrototypeOf(protoObj).otherMethod = function(){}
protoObj.__proto__.otherMethod = function() {
  console.log("this is otherMethod");
};

//3.  childObj --->  protoObj  --->  Object.prototype  --> null
let childObj = {};
Object.setPrototypeOf(childObj, protoObj);
// console.log(childObj.prop1);
// childObj.someMethod();
// childObj.otherMethod();
// childObj.nonmethod();

// 4. childObj2 ---> protoObj  ---> Object.prototype  --> null
let childObj2 = Object.create(protoObj);
console.log(childObj2.prop1); //456  coming from protoObj
childObj2.prop1 = 777; // created a new property inside childObj2 called prop1
console.log(childObj2.prop1, childObj2.__proto__.prop1);
childObj2.someMethod(); //calls the one inside protoObj
childObj2.someMethod = function() {
  console.log("new method inside childObj2");
};
childObj2.someMethod();
childObj2.__proto__.someMethod();

Thank you, so much.
It's good understanding in one video.

Thanks man!