// A function that splits an array (first argument) into groups the length of size (second argument).
// Returns as a 2D array.

function chunkArrayInGroups(arr, size)
{
    // An empty array to store our new 2D array.
    var TwoArray = [];

    // Counting through loop where to slice index and stops when reaches arr.length. Then use push() to add slice to new array.
    for (var i = 0; i < arr.length; i += size)
    {
        TwoArray.push(arr.slice(i, i + size));
    }
    return TwoArray;
}

console.log(chunkArrayInGroups(["a", "b", "c", "d"], 2));