Loops in javascript are very common and we use them a lot to cycle through arrays. Problem is most of the time we do them the wrong way.

For example: (most common use of a loop)

for ( i=0; i<=arr.length; i++ ){
       console.log(arr[i]);
}

Problem is that we are checking the length of the array everytime we cycle through, which is bad. We only need to check the length of the array once, and then continue through. Also While loops tend to be faster than for loops. So to speed things up, we should use this:

var x = arr.length;
while(x--){
       console.log(arr[x]);
}

If you noticed, we are also going in reverse so that we are not checking against a length, we are only checking that we are taking 1 integer away from the (x) variable, when we can no longer do that, we stop.

If you must go in the correct order, the following is the next quickest loop:

var i=0, len=arr.length;
while (i<len) {
    console.log(arr[i]);
}

A good article on benchmarking loops in JS:
http://blogs.oracle.com/greimer/entry/best_way_to_code_a

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qrpike

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