Grow (or shrink) an array - alters the array

Array.prototype.grow

/**
 * Grow (or shrink) an array - alters the array
 * @param {number} length
 * @param {?*...} add these entries and repeat
 * @returns this
 */
Array.prototype.grow = function(length, add) {
	var i = 0, len = this.length, args = Array.prototype.slice.call(arguments, 1);
	if (this.length < length) {
		args = args.length ? args : [0];
		while (this.length < length) {
			if (i >= args.length) {
				i = 0;
			}
			this.push(args[i++]);
		}
	} else {
		while (this.length > length) {
			this.pop();
		}
	}
	return this;
};