Javascript Array Insertion Sort

insertionSort.js

var insertionSort = function () {
    var sortedArray = [];
    var argLen = arguments.length;
    while (argLen--) { sortedArray = sortedArray.concat(arguments[argLen]); }
    var newArr = [];
    newArr.push(sortedArray[0]);
    sortedArray.slice(1, sortedArray.length).forEach(function (itemToSort) {
        var iter = newArr.length - 1;
        for (iter; iter >= 0; iter--) {
            if (itemToSort > newArr[iter]) {
                newArr.splice(iter + 1, 0, itemToSort);
                iter = 0;
            } else if (iter === 0) {
                newArr.unshift(itemToSort);
            }
        }
    });
    return newArr;
};

var foo = insertionSort(
    [1,2,3,4,11],
    [5,6,7,8]
);

console.log(foo);