How to create a new Backbone View using apply

Question

I need to create a new View instance with an arguments array. As I dont want to call

 new View(array)

I tried this solution. But unfortunately this dont work, which means no arg is passed into the initialize function. So is there away to create a new View passing in an array but have the arguments a single once in the initialize function?

Wy not just check in the `initialize` function whether the argument is, conditionally, an `Array`? — WiredPrairie, Feb 19 '13 at 11:42
Cause its inconvenient, the model should not know about how it was created. — Andreas Köberle, Feb 19 '13 at 11:45
It certainly would be typical Javascript code. As you cannot directly do method overriding in JavaScript, this is an accepted alternative that's used very commonly. — WiredPrairie, Feb 19 '13 at 11:52
But you can call a method with an array of args using `apply`, which will result in the same arguments as call the method directly with a bunch of args. — Andreas Köberle, Feb 19 '13 at 11:57
There's no perfect solution as you saw from the linked post. JS wasn't designed for this. — WiredPrairie, Feb 19 '13 at 12:07

jevakallio · Accepted Answer · 2013-02-19T11:49:55.683

You can achieve this with a bit of prototypal trickery:

function createView() {
    var args = arguments;

    //create a factory function, so we can get the "this" context
    function Factory() { return YourViewClass.apply(this, args);}

    //assign factory prototype (essentially makes factory a YourViewClass)
    Factory.prototype = YourViewClass.prototype;

    //invoke factory function
    return new Factory();
};

var view1 = createView({model:model}, 1, 2, 3);
var view2 = createView.apply(null, argumentArray);

A general solution for instantiating any "class" (constructor function) with variable arguments:

function instantiate(ctor) {
    //strip first arg, pass rest as arguments to constructor
    var args = Array.prototype.slice.call(arguments, 1);
    function Factory() { return ctor.apply(this, args);}
    Factory.prototype = ctor.prototype;
    return new Factory();
};

//call directly
var view1 = instantiate(YourViewClass, {model:model}, 1, 2, 3);

//partially apply to create a factory for a specific view class
var viewFactory = _.partial(instantiate, YourViewClass);
var view2 = viewFactory({model:model}, 1, 2, 3);

How to create a new Backbone View using apply

1 Answers1