📝 JavaScript Objects and Prototypes (Pluralsight course) — Notes

javascript-object-and-prototypes.js

// Readonly property:

// throws TypeError when 'use strict';

var cat = {
    name: 'Fluffy'
};


Object.defineProperty(cat, 'name', {writable: false});

// writable
// enumerable
// configurable

cat.name = 'zzz';

console.log(cat.name); // Fluffy

// Property with getter-setter (getter / setter are optional):

Object.defineProperty(cat, 'fullName',{
	get: function() {
		return this.name.first + ' ' + this.name.last
	},
	set: function(value) {
		var nameParts = value.split(' ');
		this.name.first = nameParts[0];
		this.name.last = nameParts[1];
	}
})

// Prototypes (I haven't compiled it):

/*
A function's prototype:
    IS the object instance that will become the prototype for all objects created using this function as a constructor.

An object's prototype:
    IS the object instance from which the object is inherited.
 */

function Cat() {}

Cat.prototype.age = 4;

var fluffy = new Cat();

fluffy.age = 5;

display(fluffy.age); // 5
display(fluffy.__proto__.age) // 4

// More on prototypes:

fluffy.hasOwnProprtty('age')
fluffy.__proto__.age = 4
Cat.prototype.constructor = Cat
x.__proto__.__proto__ //...

// MORE:
// ====================

// functions are also properties
Object.create
Object.configurable
Object.freeze
Object.keys
delete cat.name
x instanceof y