How to Change a Value in a JavaScript Array of Multiple Values

Question

I have a JavaScript array that can be built using this code

var Test = [];
Test.push([3, 2]);
Test.push([5, 7]);
Test.push([8, 1]);
Test.push([4, 10]);

What I need to do is change the first value in each item to be in order from 0, the result should look like this:

[0, 2]
[1, 7]
[2, 1]
[3, 10]

I will also accept a jQuery answer.

Answer 1

for (var i=0, l=Test.length; i<l; i++){
    Test[i][0] = i;
}

Answer 2

for (var i=0; i < Test.length; i++) {
    Test[i][0] = i;
}

Answer 3

If you want a jquery-ic answer:

  $(Test).each(function(i) {
        this[0] = i;
    });

The thing I like about this approach is that the each method creates a separate function scope for each loop iteration. Though it is not necessary in this example, it can help reduce headaches caused by unintended variable binding.

INCORRECT - Though works

 $(Test).each(function(i) {
        this[0] = i++;
    });