JavaScript Array Object

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The Array object is used to store multiple values in a single variable.

Create an array, and assign values to it:

Example

var mycars = new Array();
mycars[0] = "Saab";
mycars[1] = "Volvo";
mycars[2] = "BMW";

You will find more examples at the bottom of this page.

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What is an Array?

An array is a special variable, which can hold more than one value at a time.

If you have a list of items (a list of car names, for example), storing the cars in single variables could look like this:

var car1="Saab";
var car2="Volvo";
var car3="BMW";

However, what if you want to loop through the cars and find a specific one? And what if you had not 3 cars, but 300?

The solution is an array!

An array can hold many values under a single name, and you can access the values by referring to an index number.

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Create an Array

An array can be created in three ways.

The following code creates an Array object called myCars:

1: Regular:

var myCars=new Array();
myCars[0]="Saab";      
myCars[1]="Volvo";
myCars[2]="BMW";

2: Condensed:

var myCars=new Array("Saab","Volvo","BMW");

3: Literal:

var myCars=["Saab","Volvo","BMW"];

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Access an Array

You refer to an element in an array by referring to the index number.

This statement access the value of the first element in myCars:

var name=myCars[0];

This statement modifies the first element in myCars:

myCars[0]="Opel";

	[0] is the first element in an array. [1] is the second . . . . . (indexes start with 0)

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You Can Have Different Objects in One Array

All JavaScript variables are objects. Array elements are objects. Functions are objects.

Because of this, you can have variables of different types in the same Array.

You can have objects in an Array. You can have functions in an Array. You can have arrays in an Array:

myArray[0]=Date.now;
myArray[1]=myFunction;
myArray[2]=myCars;

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Array Methods and Properties

The Array object has predefined properties and methods:

var x=myCars.length             // the number of elements in myCars
var y=myCars.indexOf("Volvo")   // the index position of "Volvo"

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Create New Methods

Prototype is a global constructor in JavaScript. It can construct new properties and methods for any JavaScript Objects.

Example: Make a new Array method.

Array.prototype.ucase=function()
{
  for (i=0;i<this.length;i++)
  {this[i]=this[i].toUpperCase();}
}

The example above makes a new array method that transforms array values into upper case.