Monitor the invocation of the render function in a Backbone.js view in real-time

I am attempting to dynamically enhance the render function of a Backbone.js view. My goal is to trigger an event both before and after the render function is called. I have experimented with overriding the function and invoking the old function, which does work, but it results in all models that are bound to the render function losing their bindings. The current code I am using is as follows, where I provide a created Backbone.js view:

function extendRender(view) {

    view.render = (function() {
        var cachedRender = view.render;

        return function() {
            console.log("before render");
            cachedRender.apply(this, arguments);
            console.log("after render");
        };
    }());
}

While the above code functions properly, it causes issues with any models that are bound to the render function using:

    this.model.on('change', this.render, this);

This set up breaks these bindings. The only workaround I have discovered is to rebind the .on('change') event of the model after the function override. However, not every view's model will be bound in this specific way. Any guidance on this matter would be greatly appreciated! Thank you!

Answer №1

What exactly do you mean by 'break' ? Does your previous render code still get called when the model changes?

The reason for this is that the function bound to the 'change' event remains the same, even though you are only changing the property 'render' of your view and not what actually executes on change. Perhaps it would work if your binding was:

this.model.on('change', function(){return this.render()}, this)

However, I fail to see the reasoning behind this approach. In my view, using inheritance to implement common behaviors is a better option.

For instance, consider the following simplified example:

var MyBaseView = Backbone.View.extend({
  ...
  render: function(){
    this.trigger('beforeRender');
    this.beforeRender()

    //do something generic
    ...

    this.afterRender()
    this.trigger('afterRender');
  }
  ...
});

var MyOtherView = MyBaseView.extend({
  ...
  beforeRender: function(){
    //perform specific tasks here
  }

  //do NOT override "render"

  afterRender: function(){
    //perform other specific tasks here
  }
  ...
});

A more efficient solution can be found in this resource: Backbone.js view inheritance

You may also want to explore https://github.com/tbranyen/backbone.layoutmanager as it offers many features that align with your objectives.

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