Orderby JavaScript function

orderby.js

var orderBy = function(arr, keys, orders) {
	var defaultOrder = 'asc',
		newArr,
		length,
		i,
		commonOrder;


	if ('length' in arr && typeof arr == 'object') {
		if (!(orders instanceof Array)) {
			commonOrder = orders || defaultOrder;
		}

		length = arr.length;

		newArr = Array(length);

		for(i = 0; i < length; i++) {
			newArr = arr[i];
		}

		if(!keys) return newArr;

		keys = keys instanceof Array ? keys : [keys];

		return newArr.sort(function(a, b) {
			var length = keys.length,
				i,
				order,
				key;

			if(a && b) {
				for (i = 0; i < length; i++) {
					key = keys[i];
					order = (commonOrder || orders[i] || defaultOrder) == 'asc' ? -1 : 1;

					if (a[key] > b[key]) {
						return -order;
					} else if (a[key] < b[key]) {
						return order;
					}
				}
			}

			return 0;
		});
	} else {
		return [];
	}
};

This looks great. Please can you provide a quick example of how to use it?