Javascript Array setItem(key, value, new_value)

Array.prototype.setItem = function(key, value, new_value) {
    for (var i=0; i < this.length; i++) {
        if (this[i][key] === value) {
            this[i] = new_value;/*w  w  w . ja v a2 s.  co  m*/
            return;
        }
    }
}