how to delegate a “load” DOM event?

问题

I would like to call a function when a "load" event is triggered:

events: {
    "load #eventPicture" : "_resizeHeaderPic"
}

I don't want to do something like this.$("#eventPicture").on("load", _resizeHeaderPic); because I have a lot of views (it's a Single Page App) and I could go back to show another view before the image was loaded. So, if I then come back to this view I would have two listener for that "load" event. Right? By putting everything in my events hash, I can undelegate properly. But it seems that "load #eventPicture" does not work. Any suggestion?

回答1:

You cannot track load event from Backbone events because this event fires only on image instance and doesn't bubble. So Backbone.View's $el cannot track it.

jQuery callback on image load (even when the image is cached)

UPDATE

I would suggest to use another concept (JSFiddle). This is best practice:

var LayoutView = Backbone.View.extend({
    el : '[data-container]',
    show : function (view) {
        // remove current view
        this.$view && this.$view.remove();
        // save link to the new view
        this.$view = view;
        // render new view and append to our element
        this.$el.html(this.$view.render().el);
    }
});

var ImageView = Backbone.View.extend({
    template : _.template('<img src="https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-prn2/1375054_4823566966612_1010607077_n.jpg"/>'),
    render : function () {
        this.$el.html(this.template());
        this.$('img').on('load', _.bind(this.onLoad, this));
        return this;
    },
    onLoad : function () {
        console.log('onLoad');
    }
});

var OtherView = Backbone.View.extend({
    template : _.template('lalala'),
    render : function () {
        this.$el.html(this.template());
        return this;
    }
});

var Router = Backbone.Router.extend({
    routes : {
        'other' : 'other',
        '*any' : 'image'
    },
    initialize : function (options) {
        this.layout = new LayoutView();
    },
    other : function () {
        this.layout.show(new OtherView());
    },
    image : function () {
        this.layout.show(new ImageView());
    }
});

new Router();
Backbone.history.start();

来源：https://stackoverflow.com/questions/19335702/how-to-delegate-a-load-dom-event

标签

backbone.js

backbone-views