JavaScript: Multi-dimensional Array

17 Comments / JavaScript Tips & Tutorials / By /

In JavaScript, you initiate an array of 3 elements by:

var myArray = new Array(3);

Or:

var myArray = ['', '', ''];

And then to populate them with some values, you need:

for (var i = 0; i < 3; i++) {
	myArray[i] = i;
}

This is pretty much a single dimensional array. To create a multi-dimensional array such as a 2 dimensional one, you need to add one more dimension, initiating yet another array for each of the 1st-dimension elements:

var myArray = new Array(3);

for (var i = 0; i < 3; i++) {
	myArray[i] = new Array(3);
	for (var j = 0; j < 3; j++) {
		myArray[i][j] = '';
	}
}

A more straightforward approach is to directly assign values to multi-dimensional array variables:

myArray[0][0] = '';
myArray[0][1] = '';
myArray[0][2] = '';
myArray[1][0] = '';
myArray[1][1] = '';
myArray[1][2] = '';
myArray[2][0] = '';
myArray[2][1] = '';
myArray[2][2] = '';

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17 thoughts on “JavaScript: Multi-dimensional Array”

  1. Rajiva

    HOw to create like PHP style >>
    $new_array=array(0=>”Hi”,1=>”all”,2=>”my”,3=>”name”,4=>”is”,5=>”Rajiva”);

    ?? Any sugestion?

  2. Andruxa

    $new_array=array(0=>”Hi”,1=>”all”,2=>”my”,3=>”name”,4=>”is”,5=>”Rajiva”);

    var new_array = {
    0: “Hi”,
    1: “all”,
    2: “my”,
    3: “name”,
    4: “is”,
    5: “Andrey”
    };

  3. Dave

    Hi,

    Thanks for the information. I would suggest never presenting an example when the array is a square, e.g. 3×3. Use 2×3 or 3×4 or whatever. When it’s a square (e.g. 3×3), then when one sees the parameter “3”, it isn’t immediately obvious if that’s the column number or the row number.

    Thanks.

    Dave

    1. Josh

      Actually, there is no such thing as ‘row’ and ‘column’ for arrays.
      They are simply [‘first dimension identifier’] and [‘second dimension identifier’]

  4. alec berg

    Thanks for the info. I’m usually a VBA/ASP developer and the syntax for arrays is a bit unintuitive.

    In vba you just say Dim myArray(3,3)

    and your done.

  6. Daniel

    A simpler way to create a multi dimensional array is like this:

    var myArray = new Array(new Array(new Array())));

    myArray[1][2][3] = “the 3rd dimension”;

  7. Jon Roland

    I want something, such as a jquery script, that executes a python script that does nothing more than immediately display a line of HTML chosen based on the url of the calling HTML page, immediately upon page open or refresh, a different line for each URL. Initially, it can show just the URL, but the eventual solution is to use the URL as a dictionary key to select the line as a value of that dictionary.

  8. Pomax

    on a technical note, the use of new Array() is highly discouraged these days, and the format is instead just

    var myarray = [];
    var i = 3;
    while(i–>0) { myarray[i] = i; }

    As there is no such thing as a size-restricted array in JavaScript, using new Array(size) actually “lies” about what your code will do.

    Additionally, putting a “var i” inside a for loop doesn’t do the same as most programming language: variables are function-scoped, not logic-scoped, so for(var i; …) is the same as

    var i;
    for(;i<…) { … }

  9. Eduardo Mozart de Oliveira

    Thank you! Your post was very useful for me.

    Another way to create Multidimensional arrays:


    // Adapted from VBScript: Multidimensional array: http://camie.dyndns.org/technical/vbscript-arrays/
    // https://www.kavoir.com/2009/02/javascript-multi-dimensional-array.html
    var section = new Array(1);
    var key = new Array(1);

    section[1] = ["i18n"];
    key[1] = ["Load"];

    // add array key to section.
    // array inside array
    section[1] = key;

    section[1][1] = language;
    alert("Section[i18n][Load]: " + section[1][1]);

  10. christophe

    var myvar =
    {
    “yes”:{“a”:[‘g’,’h’],’b’:[‘i’,’j’],’c’:[‘k’,’l’,’m’]},
    “no “:{“a”:[‘g’,’h’],’b’:[‘i’,’j’],’c’:[‘k’,’l’,’m’]},
    };
    app.alert(myvar[“yes”][“a”]);

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