util.js

/****************************
 * Util Functions           *
 ****************************/

Array.prototype.shuffle = function() {
    for(var j, x, i = this.length-1; i; j = randomNumber(i), x = this[--i], this[i] = this[j], this[j] = x);
    return this;
};

Array.prototype.swap = function (x, y) {
    if(x>this.length || y>this.length || x === y) {return}
    var tem = this[x];
    this[x] = this[y];
    this[y] = tem;
}

Array.prototype.clone = function() {
    return this.slice(0);
}

Array.prototype.deleteByValue = function (value) {
    var pos = this.indexOf(value);
    this.splice(pos, 1);
}

Array.prototype.next = function (index) {
    if(index === this.length-1) {
        return this[0];
    } else {
        return this[index+1];
    }
}
Array.prototype.previous = function (index) {
    if(index === 0) {
        return this[this.length-1];
    } else {
      return this[index-1];
    }
}

function randomNumber(boundary) {
    return parseInt(Math.random() * boundary);
}