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Javascript arrays

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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.

JavaScript arrays are used to store multiple values in a single variable.

Creating an Array

Using an array literal is the easiest way to create a JavaScript Array.

Syntax:

var array-name = [item1, item2, ...];

Example:

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

Using the JavaScript Keyword new

The following example also creates an Array, and assigns values to it:

Example

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

Access the Elements of an Array

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

This statement accesses the value of the first element in cars:

var name = cars[0];
This statement modifies the first element in cars:

cars[0] = "Opel";
Note: [0] is the first element in an array. [1] is the second. Array indexes start with 0.


You Can Have Different Objects in One Array

JavaScript variables can be objects. Arrays are special kinds of 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;


Arrays are Objects

Arrays are a special type of objects. The typeof operator in JavaScript returns "object" for arrays.

But, JavaScript arrays are best described as arrays.

Arrays use numbers to access its "elements". In this example, person[0] returns John:

Array:
var person = ["John", "Doe", 46];


The Difference Between Arrays and Objects

  • In JavaScript, arrays use numbered indexes.
  • In JavaScript, objects use named indexes.
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