Introduction to Arrays in JavaScript

JavaScript arrays are used to store multiple values in a single variable. An array in JavaScript can hold different elements We can store Numbers, Strings and Boolean in a single array. Also arrays in JavaScript are dynamic in nature, which means its size can increase or decrease at run time.

Syntax –

Use the following syntax to create an Array object −

var fruits = [ "apple", "orange", "mango" ];
var fruits = new Array( "apple", "orange", "mango" ); // another way but not prefered
Access the Elements of an Array –

You access an array element by referring to the index number. This statement accesses the value of the first element in cars:

var cars = ["Saab", "Volvo", "BMW"];
var name = cars[0];
Access the Full Array –

With JavaScript, the full array can be accessed by referring to the array name:

var cars = ["Saab", "Volvo", "BMW"];
document.write("<h2>"+cars[i]+"</h2>");
The length Property –

The length property of an array returns the length of an array (the number of array elements).

var fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.length;                       // the length of fruits is 4
Looping Array Elements –

The safest way to loop through an array, is using a “for” loop:

var fruits, text, fLen, i;
fruits = ["Banana", "Orange", "Apple", "Mango"];
fLen = fruits.length;

text = "<ul>";
for (i = 0; i < fLen; i++) {
    text += "<li>" + fruits[i] + "</li>";
}
text += "</ul>";

 

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