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PORendering Backbone view using document fragment breaks event handling
 

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  1. PORendering Backbone view using document fragment breaks event handling
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    <p>I modified my Backbone app to render a large table using a DOM document fragment, which results in a nice performance improvement when there are many rows.</p> <p>Unfortunately, this seems to break event handling, so that the views for each row no longer receive click events. I created a <a href="http://jsfiddle.net/HAZ4G/1/" rel="nofollow">minimal example</a> to demonstrate this.</p> <p>What do I have to do to fix this?</p> <pre><code>// Javascript $(window).load(function(){ var Item = Backbone.Model.extend(); var Items = Backbone.Collection.extend({ model: Item, count: 5, initialize: function() { for(i=0; i&lt;this.count; i++){ this.add(new Item({text: i})); } } }); var ItemView = Backbone.View.extend({ tagName: 'tr', initialize: function(item) { this.item = item; }, render: function() { this.$el.append('&lt;td class="item"&gt;' + this.item.get('text') + '&lt;/td&gt;'); return this; }, events: function() { return { "click .item": function() { console.log('handling click on item '+this.item.get('text')); } }; } }); var TableBodyView = Backbone.View.extend({ tagName: 'tbody', render: function() { if(this.options.useFragment){ this.renderWithFragment(); } else { this.renderWithoutFragment(); } return this; }, renderWithFragment: function() { var fragment = document.createDocumentFragment(); this.collection.each(function(item){ fragment.appendChild((new ItemView(item)).render().el); }); this.$el.append(fragment.cloneNode(true)); }, renderWithoutFragment: function() { self = this; this.collection.each(function(item){ self.$el.append((new ItemView(item)).render().el); }); } }); var items = new Items(); $('#t1').append((new TableBodyView({collection: items, useFragment: false})).render().el); $('#t2').append((new TableBodyView({collection: items, useFragment: true})).render().el); }); // HTML &lt;table id="t1" /&gt; &lt;table id="t2" /&gt; // CSS table { float: left; margin: 10px; padding: 5px; } table#t1 { background: green; } table#t2 { background: red; } </code></pre>
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    1. USotto.poellath
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      1. VTUpMod
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    1. COI must go snowboarding right now so I can't give you a real answer. Your problem is [`cloneNode`](https://developer.mozilla.org/en-US/docs/DOM/Node.cloneNode#Notes): "Cloning a node copies all of its attributes and their values but does **not** copy event listeners."
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    2. COThanks, @muistooshort! I fixed it by using jQuery's [clone](http://docs.jquery.com/Manipulation/clone) method, which does clone event handlers if you pass in `true`: `this.$el.append($(fragment).clone(true));` Please post an answer so I can vote it up!
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      1. USotto.poellath
    3. CO@otto.poellath why do you need to clone in the first place?
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