Declare Arrays in jQuery

Sam Deering

Simple  JavaScript code snippets to delare an array. Like other JavaScript variables, you do not have to declare arrays before you can use them. I like to declare them just so I can easily read whats going on, it’s a good practice!

Example 1 – Array Constructor

// Declare an array (using the array constructor)
var arlene1 = new Array();
var arlene2 = new Array("First element", "Second", "Last");

Example 2 – Literal notatoin

// Declare an array (using literal notation)
var arlene1 = [];
var arlene2 = ["First element", "Second", "Last"];

Example 3 – Implicit Declaration

// Create an array from a method's return value
var carter = "I-learn-JavaScript";
var arlene3 = carter.split("-");

To avoid script errors, you should get into the habit of initializing an array when you declare it, like so:

// Declare an empty array using literal notation:
var arlene = [];
// The variable now contains an array of length zero

After checking my code on jslint.com I found out it says declaring an array with an array constructor is seen as bad practise! It suggests using literal notation.

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  • Kars

    Hello JQuery4U. I like playing around with arrays. I just made my first 4 dimensional one :)
    Why would not declaringvar arlene = []; give script errors? Is that in case it would contain variables that could be empty? Like so: var arlene = var1,var2,var3];

  • Kars

    after checking my code on jslint.com I found out it says declaring an array with an array constructor is seen as bad practise! It suggests using literal notation.

  • DD

    fast question where is jquery in this examples?

    • http://jquery4u.com/ jQuery4u

      It’s plain JS

  • Naveen

    Thanks :-)

  • nikhiljoshi

    Hey thankas your Posts really helpus obn many ways to learn lost of stuff

  • Ben

    Hi. I have a 2D array, i want to assign it to a variable, such that,

    var test=arr[0][0];

    when i want to print out the value of test, it give me undefined value. where did i go wrong? thanks in advanced.

  • Kelly Clover

    For some reason I can’t get jQuery to download on my computer. I want to get rid of any and all plugins that use jQuery. Google Pagespeed Insights blames jQuery heavily for page speed problems.