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JavaScript Objects


Real Life Objects, Properties, and Methods

In real life, a car is an object.

A car has properties like weight and color, and methods like start and stop:

Object Properties Methods

car.name = Fiat

car.model = 500

car.weight = 850kg

car.color = white

car.start()

car.drive()

car.brake()

car.stop()

All cars have the same properties, but the property values differ from car to car.

All cars have the same methods, but the methods are performed at different times.


JavaScript Objects

You have already learned that JavaScript variables are containers for data values.

This code assigns a simple value (Fiat) to a variable named car:

var car = "Fiat";

Try it Yourself »

Objects are variables too. But objects can contain many values.

This code assigns many values (Fiat, 500, white) to a variable named car:

var car = {type:"Fiat", model:500, color:"white"};

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The values are written as name:value pairs (name and value separated by a colon).

Note JavaScript objects are containers for named values.


Object Properties

The name:values pairs (in JavaScript objects) are called properties.

var person = {firstName:"John", lastName:"Doe", age:50, eyeColor:"blue"};

Property Property Value
firstName John
lastName Doe
age 50
eyeColor blue


Object Methods

Methods are actions that can be performed on objects.

Methods are stored in properties as function definitions.

Property Property Value
firstName John
lastName Doe
age 50
eyeColor blue
fullName function() {return this.firstName + " " + this.lastName;}

Note JavaScript objects are containers for named values, called properties and methods.


Object Definition

You define (and create) a JavaScript object with an object literal:

Example

var person = {firstName:"John", lastName:"Doe", age:50, eyeColor:"blue"};

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Spaces and line breaks are not important. An object definition can span multiple lines:

Example

var person = {
    firstName:"John",
    lastName:"Doe",
    age:50,
    eyeColor:"blue"
};

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Accessing Object Properties

You can access object properties in two ways:

objectName.propertyName()

or

objectName[propertyName()]

Example1

person.lastName;

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Example2

person["lastName"];

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Accessing Object Methods

You access an object method with the following syntax:

objectName.methodName()

Example

name = person.fullName();

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

Example

name = person.fullName;

Try it Yourself »

Note You will learn much more about objects later in this tutorial.


Try it Yourself Summary

Create a JavaScript variable

Create a JavaScript object

Create a person object (single line)

Create a person object (multiple lines)

Accessing object properties with .property

Accessing object properties with [property]

Access a function property as a method

Access a function property as a property



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