Object Methods

JavaScript Object Methods

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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() {return this.firstName + " " + this.lastName;}

Methods are functions stored as object properties.

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The this Keyword

In JavaScript, the thing called this, is the object that "owns" the JavaScript code.

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

Note that this is not a variable. It is a keyword. You cannot change the value of this.

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Accessing Object Methods

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();

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

Example

name = person.fullName;

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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!

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Adding a Method to an Object

Adding a new method to an object is easy:

Example

person.name = function () {
    return this.firstName + " " + this.lastName;
};

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