JavaScript Object Methods

Example

var person = {
  firstName: "Bill",
  lastName : "Gates",
  id       : 648,
  fullName : function() {
    return this.firstName + " " + this.lastName;

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JavaScript methods

JavaScript methods are actions that can be performed on objects.

JavaScript MethodisFunction definitionproperties.

Property value
firstName Bill
lastName Gates
age 62
eyeColor blue
fullName function() {return this.firstName + " " + this.lastName;}

Methods are functions stored as object properties.

this keyword

in JavaScript, is called this things, refers to the object that owns the JavaScript code.

this value, when used in a function, is the object that "owns" the function.

Please note this is not a variable. It is a keyword. You cannot change this value.

Access object methods

Please use the following syntax to create object methods:

methodName : function() { Code line

Please use the following syntax to access object methods:

objectName.methodName()

You usually describe fullName() as a method of the person object, and fullName as a property.

The fullName property is executed as a function when called with ()

This example accesses person object's fullName() Method:

Example

name = person.fullName();

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If you access fullName PropertyIf () is not used when defining a function, it will returnFunction definition:

Example

name = person.fullName;

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Use built-in methods

This example uses the String object's toUpperCase() Method, convert text to uppercase:

var message = "Hello world!";
var x = message.toUpperCase();

The value of x will be after the above code is executed:

HELLO WORLD!

Add New Method

Adding methods to objects is done within the constructor function:

Example

function person(firstName, lastName, age, eyeColor) {
    this.firstName = firstName;  
    this.lastName = lastName;
    this.age = age;
    this.eyeColor = eyeColor;
    this.changeName = function (name) {
        this.lastName = name;

The value of the name parameter of the changeName() function is assigned to the lastName property of the person.

Now you can try:

myMother.changeName("Jobs");

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By using 'myMother' instead of 'this', JavaScript makes it clear which person you are referring to.