Fastest JavaScript summation

Question

What is the fastest way to sum up an array in JavaScript? A quick search turns over a few different methods, but I would like a native solution if possible. This will run un

Answer 1

The fastest loop, according to this test is a while loop in reverse

var i = arr.length; while (i--) { }

So, this code might be the fastest you can get

Array.prototype.sum = function () {
    var total = 0;
    var i = this.length; 

    while (i--) {
        total += this[i];
    }

    return total;
}

Array.prototype.sum adds a sum method to the array class... you could easily make it a helper function instead.