A simple extension of the javascript Number class for ease of generating random numbers.

gistfile1.js

// Example use
// var arr = [1, 2, 3, 4, 5];
// var len = arr.length;
// var item = arr[len.random()];

Number.prototype.random = function(inc) {
    var val = (inc) ? 1 : 0;
    return Math.floor(Math.random() * (this.valueOf() + val));
};