JavaScript Two Dimensional Array

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The JavaScript Reference does not specify any effective two-dimensional array. However, you can create one. I show you how to do that in this article.

You need to already know the meaning of one and two-dimensional arrays in order to understand this article.

Note: If you cannot see the code or if you think anything is missing in this article (broken link, image absent), just contact me at That is, contact me for the slightest problem you have about what you are reading.

The One Dimensional Array
The JavaScript reference specifies a one-dimensional array. Normally each element of the one-dimensional array is a literal (value). Now, here is the secret for a two-dimensional array: If you have a one-dimensional array and you make each element of the one-dimensional array, a new array, then you would have a two dimensional array.

Creating a Two-Dimensional Array
You start by creating a one-dimensional array as follows:

twoDArr = new Array();

Assume that you want a two-dimensional array of five rows; you would make five elements of the twoDArr array, new one-dimensional arrays, using the new operator. You do this:

twoDArr[0] = new Array();
twoDArr[1] = new Array();
twoDArr[2] = new Array();
twoDArr[3] = new Array();
twoDArr[4] = new Array();

With this you have a two-dimensional array. It is a rather long process compared to what you have in other languages, but you finally got your two dimensional array.

Note: With JavaScript you do not have to decide on the length of a one or two-dimensional array. So the above two-dimensional array code is OK. If you know the number of rows and if they are many, then assigning a new one-dimensional array for each row as done above would be tedious. You solve this problem by assigning the new one-dimensional arrays in a for-loop. In this light, the above two-dimensional array is created as follows:

twoDArr = new Array();

for (i=0; i<5; ++i)
twoDArr[i]= new Array();

Accessing Values
You access the value of a JavaScript 2D array as follows:


where i is the row number and j is the column number. Row and column counting begins from zero.

So to access the value in row 2, column 4, for the above array, you would type,


Example Code
Try the following code:

Generally, you would use a two-dimensional array, when you have data in the form of a table (grid).

That is it; a rather long approach, but you still have what you want.



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