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<h1>Backbone Tutorials</h1>
<p class="homepagedescription">This site is by no means the definitive guide to backbone.js and all corrections and contributions are welcome.</p>
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<h2>What is a view?</h2>
<p>Backbone views are used to reflect what your applications’ data models look like. They are also used to listen to events and react accordingly. This tutorial will not be addressing how to bind models and collections to views but will focus on view functionality and how to use views with a JavaScript templating library, specifically <a href="http://documentcloud.github.com/underscore/#template">Underscore.js’s _.template</a>.</p>
<p>We will be using <a href="http://jquery.com/">jQuery 1.5</a> as our <span class="caps">DOM</span> manipulator. It’s possible to use other libraries such as <a href="http://mootools.net/">MooTools</a> or <a href="http://sizzlejs.com/">Sizzle</a>, but official Backbone.js documentation endorses jQuery. Backbone.View events may not work with other libraries other than jQuery.</p>
<p>For the purposes of this demonstration, we will be implementing a search box. <a href="http://jsfiddle.net/thomas/C9wew/6">A live example</a> can be found on jsFiddle.</p>
<div class="highlight"><pre><code class="javascript"> <span class="nx">SearchView</span> <span class="o">=</span> <span class="nx">Backbone</span><span class="p">.</span><span class="nx">View</span><span class="p">.</span><span class="nx">extend</span><span class="p">({</span>
<span class="nx">initialize</span><span class="o">:</span> <span class="kd">function</span><span class="p">(){</span>
<span class="nx">alert</span><span class="p">(</span><span class="s2">"Alerts suck."</span><span class="p">);</span>
<span class="p">}</span>
<span class="p">});</span>
<span class="c1">// The initialize function is always called when instantiating a Backbone View.</span>
<span class="c1">// Consider it the constructor of the class.</span>
<span class="kd">var</span> <span class="nx">search_view</span> <span class="o">=</span> <span class="k">new</span> <span class="nx">SearchView</span><span class="p">;</span>
</code></pre>
</div>
<h4>The “el” property</h4>
<p>The “el” property references the <span class="caps">DOM</span> object created in the browser. Every Backbone.js view has an “el” property, and if it not defined, Backbone.js will construct its own, which is an empty div element.</p>
<p>Let us set our view’s “el” property to div#search_container, effectively making Backbone.View the owner of the <span class="caps">DOM</span> element.</p>
<div class="highlight"><pre><code class="html"><span class="nt"><div</span> <span class="na">id=</span><span class="s">"search_container"</span><span class="nt">></div></span>
<span class="nt"><script </span><span class="na">type=</span><span class="s">"text/javascript"</span><span class="nt">></span>
<span class="nx">SearchView</span> <span class="o">=</span> <span class="nx">Backbone</span><span class="p">.</span><span class="nx">View</span><span class="p">.</span><span class="nx">extend</span><span class="p">({</span>
<span class="nx">initialize</span><span class="o">:</span> <span class="kd">function</span><span class="p">(){</span>
<span class="nx">alert</span><span class="p">(</span><span class="s2">"Alerts suck."</span><span class="p">);</span>
<span class="p">}</span>
<span class="p">});</span>
<span class="kd">var</span> <span class="nx">search_view</span> <span class="o">=</span> <span class="k">new</span> <span class="nx">SearchView</span><span class="p">({</span> <span class="nx">el</span><span class="o">:</span> <span class="nx">$</span><span class="p">(</span><span class="s2">"#search_container"</span><span class="p">)</span> <span class="p">});</span>
<span class="nt"></script></span>
</code></pre>
</div>
<p><strong>Note</strong>: Keep in mind that this binds the container element. Any events we trigger must be in this element.</p>
<h4>Loading a template</h4>
<p>Backbone.js is dependent on Underscore.js, which includes its own micro-templating solution. Refer to <a href="http://documentcloud.github.com/underscore/">Underscore.js’s documentation</a> for more information.</p>
<p>Let us implement a “render()” function and call it when the view is initialized. The “render()” function will load our template into the view’s “el” property using jQuery.</p>
<div class="highlight"><pre><code class="html"><span class="nt"><div</span> <span class="na">id=</span><span class="s">"search_container"</span><span class="nt">></div></span>
<span class="nt"><script </span><span class="na">type=</span><span class="s">"text/javascript"</span><span class="nt">></span>
<span class="nx">SearchView</span> <span class="o">=</span> <span class="nx">Backbone</span><span class="p">.</span><span class="nx">View</span><span class="p">.</span><span class="nx">extend</span><span class="p">({</span>
<span class="nx">initialize</span><span class="o">:</span> <span class="kd">function</span><span class="p">(){</span>
<span class="k">this</span><span class="p">.</span><span class="nx">render</span><span class="p">();</span>
<span class="p">},</span>
<span class="nx">render</span><span class="o">:</span> <span class="kd">function</span><span class="p">(){</span>
<span class="c1">// Compile the template using underscore</span>
<span class="kd">var</span> <span class="nx">template</span> <span class="o">=</span> <span class="nx">_</span><span class="p">.</span><span class="nx">template</span><span class="p">(</span> <span class="nx">$</span><span class="p">(</span><span class="s2">"#search_template"</span><span class="p">).</span><span class="nx">html</span><span class="p">(),</span> <span class="p">{}</span> <span class="p">);</span>
<span class="c1">// Load the compiled HTML into the Backbone "el"</span>
<span class="k">this</span><span class="p">.</span><span class="nx">el</span><span class="p">.</span><span class="nx">html</span><span class="p">(</span> <span class="nx">template</span> <span class="p">);</span>
<span class="p">}</span>
<span class="p">});</span>
<span class="kd">var</span> <span class="nx">search_view</span> <span class="o">=</span> <span class="k">new</span> <span class="nx">SearchView</span><span class="p">({</span> <span class="nx">el</span><span class="o">:</span> <span class="nx">$</span><span class="p">(</span><span class="s2">"#search_container"</span><span class="p">)</span> <span class="p">});</span>
<span class="nt"></script></span>
<span class="nt"><script </span><span class="na">type=</span><span class="s">"text/template"</span> <span class="na">id=</span><span class="s">"search_template"</span><span class="nt">></span>
<span class="o"><</span><span class="nx">label</span><span class="o">></span><span class="nx">Search</span><span class="o"><</span><span class="err">/label></span>
<span class="o"><</span><span class="nx">input</span> <span class="nx">type</span><span class="o">=</span><span class="s2">"text"</span> <span class="nx">id</span><span class="o">=</span><span class="s2">"search_input"</span> <span class="o">/></span>
<span class="o"><</span><span class="nx">input</span> <span class="nx">type</span><span class="o">=</span><span class="s2">"button"</span> <span class="nx">id</span><span class="o">=</span><span class="s2">"search_button"</span> <span class="nx">value</span><span class="o">=</span><span class="s2">"Search"</span> <span class="o">/></span>
<span class="nt"></script></span>
</code></pre>
</div>
<p><strong>Tip</strong>: Place all your templates in a file and serve them from a <span class="caps">CDN</span>. This ensures your users will always have your application cached.</p>
<h4>Listening for events</h4>
<p>To attach a listener to our view, we use the “events” attribute of Backbone.View. Remember that event listeners can only be attached to child elements of the “el” property. Let us attach a “click” listener to our button.</p>
<div class="highlight"><pre><code class="html"><span class="nt"><div</span> <span class="na">id=</span><span class="s">"search_container"</span><span class="nt">></div></span>
<span class="nt"><script </span><span class="na">type=</span><span class="s">"text/javascript"</span><span class="nt">></span>
<span class="nx">SearchView</span> <span class="o">=</span> <span class="nx">Backbone</span><span class="p">.</span><span class="nx">View</span><span class="p">.</span><span class="nx">extend</span><span class="p">({</span>
<span class="nx">initialize</span><span class="o">:</span> <span class="kd">function</span><span class="p">(){</span>
<span class="k">this</span><span class="p">.</span><span class="nx">render</span><span class="p">();</span>
<span class="p">},</span>
<span class="nx">render</span><span class="o">:</span> <span class="kd">function</span><span class="p">(){</span>
<span class="kd">var</span> <span class="nx">template</span> <span class="o">=</span> <span class="nx">_</span><span class="p">.</span><span class="nx">template</span><span class="p">(</span> <span class="nx">$</span><span class="p">(</span><span class="s2">"#search_template"</span><span class="p">).</span><span class="nx">html</span><span class="p">(),</span> <span class="p">{}</span> <span class="p">);</span>
<span class="k">this</span><span class="p">.</span><span class="nx">el</span><span class="p">.</span><span class="nx">html</span><span class="p">(</span> <span class="nx">template</span> <span class="p">);</span>
<span class="p">},</span>
<span class="nx">events</span><span class="o">:</span> <span class="p">{</span>
<span class="s2">"click input[type=button]"</span><span class="o">:</span> <span class="s2">"doSearch"</span>
<span class="p">},</span>
<span class="nx">doSearch</span><span class="o">:</span> <span class="kd">function</span><span class="p">(</span> <span class="nx">event</span> <span class="p">){</span>
<span class="c1">// Button clicked, you can access the element that was clicked with event.currentTarget</span>
<span class="nx">alert</span><span class="p">(</span> <span class="s2">"Search for "</span> <span class="o">+</span> <span class="nx">$</span><span class="p">(</span><span class="s2">"#search_input"</span><span class="p">).</span><span class="nx">val</span><span class="p">()</span> <span class="p">);</span>
<span class="p">}</span>
<span class="p">});</span>
<span class="kd">var</span> <span class="nx">search_view</span> <span class="o">=</span> <span class="k">new</span> <span class="nx">SearchView</span><span class="p">({</span> <span class="nx">el</span><span class="o">:</span> <span class="nx">$</span><span class="p">(</span><span class="s2">"#search_container"</span><span class="p">)</span> <span class="p">});</span>
<span class="nt"></script></span>
<span class="nt"><script </span><span class="na">type=</span><span class="s">"text/template"</span> <span class="na">id=</span><span class="s">"search_template"</span><span class="nt">></span>
<span class="o"><</span><span class="nx">label</span><span class="o">></span><span class="nx">Search</span><span class="o"><</span><span class="err">/label></span>
<span class="o"><</span><span class="nx">input</span> <span class="nx">type</span><span class="o">=</span><span class="s2">"text"</span> <span class="nx">id</span><span class="o">=</span><span class="s2">"search_input"</span> <span class="o">/></span>
<span class="o"><</span><span class="nx">input</span> <span class="nx">type</span><span class="o">=</span><span class="s2">"button"</span> <span class="nx">id</span><span class="o">=</span><span class="s2">"search_button"</span> <span class="nx">value</span><span class="o">=</span><span class="s2">"Search"</span> <span class="o">/></span>
<span class="nt"></script></span>
</code></pre>
</div>
<h4>Tips and Tricks</h4>
<p><strong>Using template variables</strong></p>
<div class="highlight"><pre><code class="html"><span class="nt"><div</span> <span class="na">id=</span><span class="s">"search_container"</span><span class="nt">></div></span>
<span class="nt"><script </span><span class="na">type=</span><span class="s">"text/javascript"</span><span class="nt">></span>
<span class="nx">SearchView</span> <span class="o">=</span> <span class="nx">Backbone</span><span class="p">.</span><span class="nx">View</span><span class="p">.</span><span class="nx">extend</span><span class="p">({</span>
<span class="nx">initialize</span><span class="o">:</span> <span class="kd">function</span><span class="p">(){</span>
<span class="k">this</span><span class="p">.</span><span class="nx">render</span><span class="p">();</span>
<span class="p">},</span>
<span class="nx">render</span><span class="o">:</span> <span class="kd">function</span><span class="p">(){</span>
<span class="c1">//Pass variables in using Underscore.js Template</span>
<span class="kd">var</span> <span class="nx">variables</span> <span class="o">=</span> <span class="p">{</span> <span class="nx">search_label</span><span class="o">:</span> <span class="s2">"My Search"</span> <span class="p">};</span>
<span class="c1">// Compile the template using underscore</span>
<span class="kd">var</span> <span class="nx">template</span> <span class="o">=</span> <span class="nx">_</span><span class="p">.</span><span class="nx">template</span><span class="p">(</span> <span class="nx">$</span><span class="p">(</span><span class="s2">"#search_template"</span><span class="p">).</span><span class="nx">html</span><span class="p">(),</span> <span class="nx">variables</span> <span class="p">);</span>
<span class="c1">// Load the compiled HTML into the Backbone "el"</span>
<span class="k">this</span><span class="p">.</span><span class="nx">el</span><span class="p">.</span><span class="nx">html</span><span class="p">(</span> <span class="nx">template</span> <span class="p">);</span>
<span class="p">},</span>
<span class="nx">events</span><span class="o">:</span> <span class="p">{</span>
<span class="s2">"click input[type=button]"</span><span class="o">:</span> <span class="s2">"doSearch"</span>
<span class="p">},</span>
<span class="nx">doSearch</span><span class="o">:</span> <span class="kd">function</span><span class="p">(</span> <span class="nx">event</span> <span class="p">){</span>
<span class="c1">// Button clicked, you can access the element that was clicked with event.currentTarget</span>
<span class="nx">alert</span><span class="p">(</span> <span class="s2">"Search for "</span> <span class="o">+</span> <span class="nx">$</span><span class="p">(</span><span class="s2">"#search_input"</span><span class="p">).</span><span class="nx">val</span><span class="p">()</span> <span class="p">);</span>
<span class="p">}</span>
<span class="p">});</span>
<span class="kd">var</span> <span class="nx">search_view</span> <span class="o">=</span> <span class="k">new</span> <span class="nx">SearchView</span><span class="p">({</span> <span class="nx">el</span><span class="o">:</span> <span class="nx">$</span><span class="p">(</span><span class="s2">"#search_container"</span><span class="p">)</span> <span class="p">});</span>
<span class="nt"></script></span>
<span class="nt"><script </span><span class="na">type=</span><span class="s">"text/template"</span> <span class="na">id=</span><span class="s">"search_template"</span><span class="nt">></span>
<span class="c"><!--</span> <span class="nx">Access</span> <span class="nx">template</span> <span class="nx">variables</span> <span class="kd">with</span> <span class="o"><%=</span> <span class="o">%></span> <span class="o">--></span>
<span class="o"><</span><span class="nx">label</span><span class="o">><%=</span> <span class="nx">search_label</span> <span class="o">%><</span><span class="err">/label></span>
<span class="o"><</span><span class="nx">input</span> <span class="nx">type</span><span class="o">=</span><span class="s2">"text"</span> <span class="nx">id</span><span class="o">=</span><span class="s2">"search_input"</span> <span class="o">/></span>
<span class="o"><</span><span class="nx">input</span> <span class="nx">type</span><span class="o">=</span><span class="s2">"button"</span> <span class="nx">id</span><span class="o">=</span><span class="s2">"search_button"</span> <span class="nx">value</span><span class="o">=</span><span class="s2">"Search"</span> <span class="o">/></span>
<span class="nt"></script></span>
</code></pre>
</div>
<p>If you have any questions, leave a comment below.</p>
<h3>Relevant Links</h3>
<ul>
<li><a href="http://documentcloud.github.com/backbone/">Backbone.js official website</a></li>
<li><a href="http://thomasdavis.github.com/2011/02/05/backbone-views-and-templates.html">This example implemented with google <span class="caps">API</span></a></li>
<li><a href="http://jsfiddle.net/thomas/C9wew/4/">This examples exact code on jsfiddle.net</a></li>
<li><a href="http://jsfiddle.net/thomas/dKK9Y/6/">Another semi-complete example on jsFiddle</a></li>
</ul>
<h3>Author</h3>
<ul>
<li><a href="https://github.com/thomasdavis">Thomas Davis</a></li>
</ul>
<h3>Contributors</h3>
<ul>
<li><a href="https://github.com/zaeleus">Michael Macias</a></li>
</ul>
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