Question

I would like to do pass a function to backbone’s success callback like this

this.model.fetch({
    success: this.setup
});

However, that won’t work I end up having to pass the whole environment and wrap inside a function like that:

var that = this;
this.model.fetch({
    success: function(){
        that.setup();
    }
});

Why can’t I do this? Even if I bind the setup function to it’s parent like so _.bind( this.setup, this );, it still won’t use the proper this (its’ parent). But only if its’ not wrapped in a function…

Answer 1

_.bind returns a function bound to an object, it does not modify the original function (basically it creates the wrapped function you wrote).

However, you could pass this bound function as a callback

this.model.fetch({
    success: _.bind(this.setup, this);
});

or use _.bindAll which does modify the object to use bound functions:

var V = Backbone.View.extend({
    initialize: function() {
        _.bindAll(this, "setup");

        this.model.fetch({
            success: this.setup
        });
    },
    setup: function() {

    }
});