Loop 'n' elements in groups in each iteration

Question

Let's say I have this array:

var arr = [1,2,3,4,5,6,7,8,9,10]

Example: I want to construct 5 arrays with each pair in it so it becomes,

arr1 = [1,2]
arr2 = [2,4]
arr3 = [5,6]

This can of course be solved with the modulo operator(%), since those are simply pairs - so it becomes:

for (var i = 0; i < arr.length; i++) {
  if(arr[i] % 2 === 0)
    window['arr' + i].push(arr[i], arr[i - 1])
}

There are other ways, e.g with nested loops etc.

I'm feeling that this can be solved with a simpler way however, so I'd like to see more suggestions

---

So what's an elegant way to loop every 'n' items in an array, perform some operation on them and then move on to the next 'n' elements.

Update:

The example above deals with 2 elements in a a 10-element array- That's purely random. I'm not looking for a way to deal with pairs in an array - The question is about how to loop every N elements in an array, perform whatever operation on those N elements and move on to the next N elements

I'm also not looking to create new arrays - The question has to do with iterating over the original array, only.

Answer 1

Use plain old for loop, like this

var N = 3;
for (var i = 0; i < array.length; i += N) {
    // Do your work with array[i], array[i+1]...array[i+N-1]
}

Answer 2

Just increment by n in your for loop:

for (var i = 0; i < arr.length; i += 2)
    console.log(arr[i], arr[i + 1]);

You can write a function to automate walking through an array by n for you:

function walk(arr, n, fn) {
    for (var i = 0; i < arr.length; i += n)
        fn(arr.slice(i, i + n));
}

walk([1,2,3,4,5,6], 2, function (segment) {
    console.log(segment);
});