I have a web app, where the user can hit a button to `copy` an engine object.

I wrote the method below in Javascript, and it works. However, if more than 2 or 3 users are cloning, random errors will pop-up. For example, it will say, `Engine is undefined` or `engineToClone is undefined`.

But if only one person is doing it, it never has errors.

So I am wondering if there is a better way to write this:

```
    var engineToClone = this.model;

    var clonedEngine = new Engine({
        factoryId: engineToClone.attributes.factoryId,
        title: 'CLONED OF - ' + engineToClone.attributes.title,
        engineDescription: engineToClone.attributes.engineDescription,
        isFrontend: engineToClone.attributes.isFrontend,
        cylinders: engineToClone.cylinders,
        headers: engineToClone.headers,
        vehicles: engineToClone.vehicles,
        pistons: engineToClone.pistons,
        fuels: engineToClone.fuels
    });

    clonedEngine.save(null, {
        url: self.factory.url()
    }).done(function () {
    });

```

I tried doing this, but it generates null values:

```
    var engineToClone = this.model;

    var clonedEngine = engineToClone;

```

But the clonedEngine is always comes back as null.

I also read an answer on here to use json, so I tried this:

```
JSON.parse(JSON.stringify(engineToClone))

```

But it always says JSON is undefined.

So I must be doing something wrong and I was hoping someone could point me in the right direction.

Thanks!