backbone console log event triggering

Asked By: Anonymous

I’ve got a underscore/backbone/require application and I would like to output all events that are triggered through backbone to the console (in other words: pass each event through console.log function). I’ve tried wrapping it with underscore and manually replacing the function. Neither this:

console.log(Backbone.Events.trigger);
var trigger = Backbone.Events.trigger;
Backbone.Events.trigger = function(name) {
    console.log('Event', name, 'triggered.');
    trigger.apply(this, arguments);
}

nor this:

Backbone.Events.trigger = _.wrap(Backbone.Events.trigger, function(func) {
    console.log('EVENT:', Array.prototype.slice.call(arguments));
    func(Array.prototype.slice.call(arguments));
});
console.log(Backbone.Events.trigger);

worked. I’d appreciate a javascript (not coffeescript) solution.

Solution

Answered By: Anonymous

Your wrappings fail because Backbone mixes in Backbone.Events behavior on Backbone.Model, Backbone.Collection, etc. For example, Backbone.Model is defined as

var Model = Backbone.Model = function(attributes, options) {
    ...
};
_.extend(Model.prototype, Events, {
    ...
};

This means that when you redefine Backbone.Events.trigger, it is already too late.

But all is not lost! You won’t be able to redefine all trigger methods in one go, but you can redefine them on class level:

Backbone.Model.prototype.trigger = function() {
    console.log('Event', arguments);
    Backbone.Events.trigger.apply(this, arguments);
}

and a demo http://jsfiddle.net/nikoshr/G2Qfn/

For a given class, you can override the trigger method:

var M = Backbone.Model.extend({
    trigger: function() {
        console.log('Event', arguments);
        Backbone.Model.prototype.trigger.apply(this, arguments);
    }
});

http://jsfiddle.net/nikoshr/G2Qfn/1/

or for a given instance

var M = Backbone.Model.extend({});

var m = new M();   
m.trigger = function() {
    console.log('Event', arguments);
    M.prototype.trigger.apply(this, arguments);
}

http://jsfiddle.net/nikoshr/G2Qfn/2/