Knockout liveMap

knockout.livemap.js

Array.prototype.liveMap = function (map, cleanUp) {
    var destination = [];
    this.map(function(item) {
        destination[destination.length] = map(item);
    });
    this.subscribe(function (changes) {
        changes.forEach(function(change) {
            if (change.status === 'added') {
                var t2 = map(change.value);
                destination.push(t2);
            //} else if (change.status === "") {
            //    destination[change.index] = map(change.value);
            } else if (change.status === "deleted") {
                var destItem = destination[change.index];
                destination.splice(change.index, 1);
                if (cleanUp) cleanUp(destItem);
            }
        });
    }, null, "arrayChange");
    return destination;
}