JavaScript Object Diff

javaScriptObjectDiff.js

// Some initial work on an object differ.

var difference = Delta(
    {
        a:{m:1},
        c:22
    },
    {
        a:{n:1},
        b:7

    }
);

console.log(JSON.stringify(difference));

/*
{
    "deltas":[
        {
            "type":"NestedDelta",
            "prop":"a",
            "deltas":[
                {"type":"RemoveProp","prop":"m"},
                {"type":"AddProp","prop":"n","value":1}
            ]
        },
        {"type":"RemoveProp","prop":"c"},
        {"type":"AddProp","prop":"b","value":7}
    ]
}
*/

function NDelta(prop, delta) {
    if (!(this instanceof NDelta)) { return new NDelta(prop, delta); }
    this.type = "NestedDelta";
    this.prop = prop;
    this.deltas = delta.deltas;
}

function Remove(prop) {
    if (!(this instanceof Remove)) { return new Remove(prop); }
    this.type = "RemoveProp";
    this.prop = prop;
}

function Change(prop, from, to) {
    if (!(this instanceof Change)) { return new Change(prop, from, to); }
    this.type = "ChangeProp";
    this.prop = prop;
    this.from = from;
    this.to = to;
}
Change.prototype.toString = function() {
    return "Change '" + this.prop + "' from " + this.v1 + " to " + this.v2;
}

function Add(prop, value) {
    if (!(this instanceof Add)) { return new Add(prop, value); }
    this.type = "AddProp";
    this.prop = prop;
    this.value = value;
}

function Delta(o1, o2) {
    if (!(this instanceof Delta)) { return new Delta(o1, o2); }
    var deltas = [];
    var o2Skip = {};
    var i;
    for (i in o1) {
        if (o1.hasOwnProperty(i)) {
            if (!o2.hasOwnProperty(i)) {
                deltas.push(Remove(i));
                continue;
            } else {
                o2Skip[i] = true;
            }
    
            if (o1[i] === o2[i]) {
                continue;
            }

            if (typeof o1[i] == 'object') {
                deltas.push.call(deltas, NDelta(i, Delta(o1[i], o2[i])));
                continue;
            }

            if (o1[i] !== o2[i]) {
                deltas.push(Change(i, o1[i], o2[i]));
            }

        }
    }

    for(i in o2) {
        if (o2Skip[i]) continue;
        if (o2.hasOwnProperty(i)) {
            deltas.push(Add(i, o2[i]));
        }
    }
    this.deltas = deltas;
}