how to correctly clone an object in WinJS

Question

I have this function for create objects in WinJS:

function BiometricSignatureData() {
    this.averageSpeed       = "";
    this.pressure           = new Array();
    this.location           = new Array();
    this.timestamp          = new Array();
    this.speed              = new Array();
    this.evt                = new Array();
    this.spaces             = 0;
    this.attackPoints       = 0;
    this.finalPoints        = 0;
    this.signatureAddress   = "";


    this.restartObject =
        function () {
            this.pressure           = new Array();
            this.location           = new Array();
            this.timestamp          = new Array();
            this.averageSpeed       = "";
            this.speed              = new Array();
            this.evt                = new Array();
            this.spaces             = 0;
            this.attackPoints       = 0;
            this.finalPoints        = 0;
            this.signatureAddress   = "";
        }
    this.printBiometricValuesOnRealTime = 
        function (pressure, location, averageSpeed, spaces, attackPoints, finishPoints) {

            pressure.value                = this.pressure[this.pressure.length -1];
            location.value                = "{" + this.location[this.location.length - 1] + "}";
            averageSpeed.value            = this.averageSpeed;
            spaces.value                  = this.spaces;
            attackPoints.value            = this.attackPoints;
            finishPoints.value            = this.finalPoints;
        }
}

Basicly creates BiometricSignatureData-type objects with 2 methods

restartObject
printBiometricValuesOnRealTime

and then I created two instances of the same object

var biometricObject         = new BiometricSignatureData();
var biometricObjectBackup   = new BiometricSignatureData();

my first instance (biometricObject) is filled with data, then I want to clone (not by reference) this instance in my second instance (biometricObjectBackup) by doing this:

function cloneObject(from, to) {// extends 'from' object with members from 'to'. If 'to' is null, a deep clone of 'from' is returned
                if (from == null || typeof from != "object") return from;
                if (from.constructor != Object && from.constructor != Array) return from;
                if (from.constructor == Date || from.constructor == RegExp || from.constructor == Function ||
                    from.constructor == String || from.constructor == Number || from.constructor == Boolean)
                    return new from.constructor(from);
                to = to || new from.constructor();
                for (var name in from) {
                    to[name] = typeof to[name] == "undefined" ? cloneObject(from[name], null) : to[name];
                }
                return to;
            }

filling second instance with first instance info

console.log("original Array: " + biometricObject.evt.length + ",  backup Array: " + biometricObjectBackup.evt.length);
biometricObjectBackup = cloneObject(biometricObject);

console.log("original Array: " + biometricObject.evt.length + ",  backup Array: " + biometricObjectBackup.evt.length);
biometricObject.restartObject();
console.log("original Array: " + biometricObject.evt.length + ",  backup Array: " + biometricObjectBackup.evt.length);

put three console.log to follow the behavior of the objects getting next output:

original Array: 10,  backup Array: 0
original Array: 10,  backup Array: 10
original Array: 0,  backup Array: 0

If I restart my original object, the second one (the cloned) cleans itself as well, how to do this right???

thanks for the support

I'm not following with all of the code and your example, but your clone doesn't handle arrays? Should it? http://stackoverflow.com/questions/4459928/how-to-deep-clone-in-javascript — WiredPrairie, Feb 13 '14 at 01:44
my clone didn't handle a copy of all its arrays, it seems it was a copy by reference, because if I affected one, then affected the other one I don't know why — Jesús Ayala, Feb 13 '14 at 16:22

score 1 · Accepted Answer · answered Feb 13 '14 at 01:20

you may try this:

var BiometricSignatureData = {
    averageSpeed:       "",
    pressure:           new Array(),
    location:           new Array(),
    timestamp:          new Array(),
    speed:              new Array(),
    evt:                new Array(),
    spaces:             0,
    attackPoints:       0,
    finalPoints:        0,
    signatureAddress:   "",


    restartObject :
        function () {
            this.pressure           = new Array();
            this.location           = new Array();
            this.timestamp          = new Array();
            this.averageSpeed       = "";
            this.speed              = new Array();
            this.evt                = new Array();
            this.spaces             = 0;
            this.attackPoints       = 0;
            this.finalPoints        = 0;
            this.signatureAddress   = "";
        },

    printBiometricValuesOnRealTime:
        function (pressure, location, averageSpeed, spaces, attackPoints, finishPoints) {

            pressure.value          = this.pressure[this.pressure.length - 1];
            location.value          = "{" + this.location[this.location.length - 1] + "}";
            averageSpeed.value      = this.averageSpeed;
            spaces.value            = this.spaces;
            attackPoints.value      = this.attackPoints;
            finishPoints.value      = this.finalPoints;
        }
}


var BiometricSignatureDataBackup;

clone function is the same

and the last part:

BiometricSignatureDataBackup = cloneObject(BiometricSignatureData);

    console.log("original Array: " + biometricObject.evt.length + ",  backup Array: " + biometricObjectBackup.evt.length);
    BiometricSignatureData.restartObject();
    console.log("original Array: " + BiometricSignatureData.evt.length + ",  backup Array: " + BiometricSignatureDataBackup.evt.length);

how to correctly clone an object in WinJS

1 Answers1