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August 20, 2018
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javascript

Object

In JavaScript, objects are pairs of keys and values. For example, I wanted to describe my name, I could have an object with two keys:

firstName would point to “Erdal” and lastName would point to “SATIK”. Keys in a JavaScript object are Strings.

To create new object in JavaScript;

var person = Object.create(null); // this creates an empty objects  

Prototypes

JavaScript objects also have one additional attribute: a pointer toanother object. We call this pointer the object’s prototype. If you try to look up a key on an object and it is not found, JavaScript will look for it in the prototype. It will follow the “prototype chain” until it sees a nullvalue. In that case, it returns undefined.

So, shortly about protoypes;

  • Every JavaScript object has a prototype. The prototype is also an object.
  • All JavaScript objects inherit their properties and methods from their prototype.
  • Objects created using an object literal, or with new Object(), inherit from a prototype called Object.prototype.
  • Objects created with new Date() inherit the Date.prototype.
  • All JavaScript objects (Date, Array, RegExp, Function, ….) inherit from the Object.prototype.

Creating Prototype

The standard way to create an object prototype is to use an object constructor function:

The constructor function is the prototype for Person objects.

function Person(first, last, age, eyecolor) {this.firstName = first;this.lastName = last;this.age = age;this.eyeColor = eyecolor;}

new keyword to create new objects from the same prototype:

var myFather = new Person("John", "Doe", 50, "blue");<br />
var myMother = new Person("Sally", "Rally", 48, "green");
Adding a Property to an Object – Using the prototype Property
myFather.nationality = "English";
Adding a Method to an Object
myFather.name = function () {return this.firstName + " " + this.lastName;};
Using the prototype Property
function Person(first, last, age, eyecolor) {this.firstName = first;this.lastName = last;this.age = age;this.eyeColor = eyecolor;}

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