X

X

X

JavaScript Object Methods


JavaScript Methods

JavaScript methods are the actions that can be performed on objects.

A JavaScript method is a property containing a function definition.

Property Value
firstName John
lastName Doe
age 50
eyeColor blue
fullName function()

Methods are functions stored as object properties.


Accessing Object Methods

You create an object method with the following syntax:

methodName : function() { code lines }

You access an object method with the following syntax:

objectName.methodName()

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

The fullName property will execute (as a function) when it is invoked with ().

This example accesses the fullName() method of a person object:

Example

name = person.fullName();

Try it Yourself »

If you access the fullName property, without (), it will return the function definition:

Example

name = person.fullName;

Try it Yourself »



Using Built-In Methods

This example uses the toUpperCase() method of the String object, to convert a text to uppercase:

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

The value of x, after execution of the code above will be:

HELLO WORLD!

Adding New Methods

Adding methods to an object is done inside 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 changeName() function assigns the value of name to the person’s lastName property.

Now You Can Try:

myMother.changeName(“Doe”);

Try it Yourself »

JavaScript knows which person you are talking about by “substituting” this with myMother.