average method

by ledlogic

JavaScript

var nothing = null;
var empty = [];
var items = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]; // 20 sider
function average(items) {
    if (!items) {
        return 0;
    }
    var sum = 0,
        count = 0;
    // for large arrays, faster to go down.
    for (var count = items.length, i = count - 1; i >= 0; i--) {
        sum += items[i];
    }
    return count ? sum / count : 0;
}

alert(nothing + ":" + average(nothing) + "\r" + empty + ":" + average(empty) + "\r" + items + ":" + average(items) + "\r");