Adds default param values to a function

setDefaultArguments.js

/**
 * Default Arguments
 * Copyright (c) 2012, marlun78
 * MIT License, https://gist.github.com/marlun78/bd0800cf5e8053ba9f83
 * 
 * Set default arguments to a function
 * @param    {function}  fn         - The function to decorate
 * @param    {*}         [args...]  - Any default arguments
 * @returns  {function}             - The new decorated function
 * 
 * @example
 * var decorated = setDefaultArguments(function add(a, b) {
 *   return a + b;
 * }, 2, 2);
 * decorated();              //> 4
 * decorated(1);             //> 3
 * decorated(undefined, 0);  //> 2
 */
var setDefaultArguments = (function (undefined) {
    var arraySlice = Array.prototype.slice;
    function mask(left, right) {
        var max = Math.max(left.length, right.length);
        for (var index = 0; index < max; index++) {
            left[index] = left[index] === undefined ? right[index] : left[index];
        }
        return left;
    }
    return function (fn/* [, defaultArgs...] */) {
        var defaults = arraySlice.call(arguments, 1);
        if (typeof fn !== 'function') {
            throw new TypeError;
        }
        return function () {
            return fn.apply(this, mask(arraySlice.call(arguments), defaults));
        };
    };
}());