Two dimensional array in JavaScript displaying by for loop

Two dimensional JavaScript array

We can create two dimensional arrays in JavaScript. These arrays are different than two dimensional arrays we have used in ASP. To understand two dimensional arrays we will use some examples. First let us try to create some arrays.


var details = new Array();

details[0]=new Array(3);

details[0][0]="Example 1";

details[0][1]="Example 2";

details[0][2]="Example 3";



details[1]=new Array(2);

details[1][0]="Example 4";

details[1][1]="Example 5";

As you have seen we have declared a array and named it as details. Then we have added elements to this array. Now to access the elements we have to address them like this.

document.write(details[0][2]);

This will give the output as Example 3

Displaying elements of two dimensional array

To display the inner elements of first set of array we have to use for loop. Here is an example.


for(i=0; i<=2; i++){

document.write(details[0][i]);

document.write("<br>");

}

This will give the output as


Example 1

Example 2

Example 3

Now we will use two for loops one inside the other to display all the elements. Here is the code.

for(j=0; j<=1; j++){

for(i=0; i<=2; i++){

document.write(details[j][i]);

document.write("<br>");

}}

The output of the above code is here


Example 1

Example 2

Example 3

Example 4

Example 5

undefined

Note the last line saying undefined. This is because we have not added any element to details[1][2]

Displaying elements by using length Property

In above code we used numbers inside for loops because we already know the number of elements present inside array. If we don't know the number of elements present inside array then we can use the array length property inside for loop to display the elements.

for(j=0; j<details.length; j++){

for(i=0; i<details[j].length; i++){
document.write(details[j][i]);
document.write("<br>");
}

}

Example

var my_2d = [
  ['One', 2],
  ['Two', 4],
  ['Three', 6]
];
// display now
for(i = 0; i < my_2d.length; i++)
document.write(my_2d[i][0] + ',' + my_2d[i][1] + '<br>' );

Output

One,2
Two,4
Three,6

More on JavaScript Arrays : Create , display and Applications