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<h1>todos.js</h1>

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<p>An example Backbone application contributed by

<a href="http://jgn.me/">Jérôme Gravel-Niquet</a>. This demo uses a simple

<a href="backbone-localstorage.html">LocalStorage adapter</a>

to persist Backbone models within your browser.</p>

<p>Load the application once the DOM is ready, using <code>jQuery.ready</code>:</p>

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<div class="content"><div class='highlight'><pre>$(<span class="keyword">function</span>(){</pre></div></div>

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<h2>Todo Model</h2>

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<p>Our basic <strong>Todo</strong> model has <code>title</code>, <code>order</code>, and <code>done</code> attributes.</p>

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<div class="content"><div class='highlight'><pre> <span class="keyword">var</span> Todo = Backbone.Model.extend({</pre></div></div>

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<p>Default attributes for the todo item.</p>

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<div class="content"><div class='highlight'><pre> defaults: <span class="keyword">function</span>() {

<span class="keyword">return</span> {

title: <span class="string">"empty todo..."</span>,

order: Todos.nextOrder(),

done: <span class="literal">false</span>

};

},</pre></div></div>

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<p>Toggle the <code>done</code> state of this todo item.</p>

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<div class="content"><div class='highlight'><pre> toggle: <span class="keyword">function</span>() {

<span class="keyword">this</span>.save({done: !<span class="keyword">this</span>.get(<span class="string">"done"</span>)});

}

});</pre></div></div>

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<h2>Todo Collection</h2>

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<p>The collection of todos is backed by <em>localStorage</em> instead of a remote

server.</p>

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<div class="content"><div class='highlight'><pre> <span class="keyword">var</span> TodoList = Backbone.Collection.extend({</pre></div></div>

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<p>Reference to this collection&#39;s model.</p>

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<div class="content"><div class='highlight'><pre> model: Todo,</pre></div></div>

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<p>Save all of the todo items under the <code>&quot;todos-backbone&quot;</code> namespace.</p>

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<div class="content"><div class='highlight'><pre> localStorage: <span class="keyword">new</span> Backbone.LocalStorage(<span class="string">"todos-backbone"</span>),</pre></div></div>

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<p>Filter down the list of all todo items that are finished.</p>

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<div class="content"><div class='highlight'><pre> done: <span class="keyword">function</span>() {

<span class="keyword">return</span> <span class="keyword">this</span>.where({done: <span class="literal">true</span>});

},</pre></div></div>

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<p>Filter down the list to only todo items that are still not finished.</p>

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<div class="content"><div class='highlight'><pre> remaining: <span class="keyword">function</span>() {

<span class="keyword">return</span> <span class="keyword">this</span>.where({done: <span class="literal">false</span>});

},</pre></div></div>

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<p>We keep the Todos in sequential order, despite being saved by unordered

GUID in the database. This generates the next order number for new items.</p>

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<div class="content"><div class='highlight'><pre> nextOrder: <span class="keyword">function</span>() {

<span class="keyword">if</span> (!<span class="keyword">this</span>.length) <span class="keyword">return</span> <span class="number">1</span>;

<span class="keyword">return</span> <span class="keyword">this</span>.last().get(<span class="string">'order'</span>) + <span class="number">1</span>;

},</pre></div></div>

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<p>Todos are sorted by their original insertion order.</p>

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<div class="content"><div class='highlight'><pre> comparator: <span class="string">'order'</span>

});</pre></div></div>

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<p>Create our global collection of <strong>Todos</strong>.</p>

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<div class="content"><div class='highlight'><pre> <span class="keyword">var</span> Todos = <span class="keyword">new</span> TodoList;</pre></div></div>

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<h2>Todo Item View</h2>

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<p>The DOM element for a todo item...</p>

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<div class="content"><div class='highlight'><pre> <span class="keyword">var</span> TodoView = Backbone.View.extend({</pre></div></div>

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<p>... is a list tag.</p>

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<div class="content"><div class='highlight'><pre> tagName: <span class="string">"li"</span>,</pre></div></div>

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<p>Cache the template function for a single item.</p>

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<div class="content"><div class='highlight'><pre> template: _.template($(<span class="string">'#item-template'</span>).html()),</pre></div></div>

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<p>The DOM events specific to an item.</p>

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<div class="content"><div class='highlight'><pre> events: {

<span class="string">"click .toggle"</span> : <span class="string">"toggleDone"</span>,

<span class="string">"dblclick .view"</span> : <span class="string">"edit"</span>,

<span class="string">"click a.destroy"</span> : <span class="string">"clear"</span>,

<span class="string">"keypress .edit"</span> : <span class="string">"updateOnEnter"</span>,

<span class="string">"blur .edit"</span> : <span class="string">"close"</span>

},</pre></div></div>

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<p>The TodoView listens for changes to its model, re-rendering. Since there&#39;s

a one-to-one correspondence between a <strong>Todo</strong> and a <strong>TodoView</strong> in this

app, we set a direct reference on the model for convenience.</p>

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<div class="content"><div class='highlight'><pre> initialize: <span class="keyword">function</span>() {

<span class="keyword">this</span>.listenTo(<span class="keyword">this</span>.model, <span class="string">'change'</span>, <span class="keyword">this</span>.render);

<span class="keyword">this</span>.listenTo(<span class="keyword">this</span>.model, <span class="string">'destroy'</span>, <span class="keyword">this</span>.remove);

},</pre></div></div>

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<p>Re-render the titles of the todo item.</p>

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<div class="content"><div class='highlight'><pre> render: <span class="keyword">function</span>() {

<span class="keyword">this</span>.$el.html(<span class="keyword">this</span>.template(<span class="keyword">this</span>.model.toJSON()));

<span class="keyword">this</span>.$el.toggleClass(<span class="string">'done'</span>, <span class="keyword">this</span>.model.get(<span class="string">'done'</span>));

<span class="keyword">this</span>.input = <span class="keyword">this</span>.$(<span class="string">'.edit'</span>);

<span class="keyword">return</span> <span class="keyword">this</span>;

},</pre></div></div>

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<p>Toggle the <code>&quot;done&quot;</code> state of the model.</p>

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<div class="content"><div class='highlight'><pre> toggleDone: <span class="keyword">function</span>() {

<span class="keyword">this</span>.model.toggle();

},</pre></div></div>

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<p>Switch this view into <code>&quot;editing&quot;</code> mode, displaying the input field.</p>

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<div class="content"><div class='highlight'><pre> edit: <span class="keyword">function</span>() {

<span class="keyword">this</span>.$el.addClass(<span class="string">"editing"</span>);

<span class="keyword">this</span>.input.focus();

},</pre></div></div>

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<p>Close the <code>&quot;editing&quot;</code> mode, saving changes to the todo.</p>

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<div class="content"><div class='highlight'><pre> close: <span class="keyword">function</span>() {

<span class="keyword">var</span> value = <span class="keyword">this</span>.input.val();

<span class="keyword">if</span> (!value) {

<span class="keyword">this</span>.clear();

} <span class="keyword">else</span> {

<span class="keyword">this</span>.model.save({title: value});

<span class="keyword">this</span>.$el.removeClass(<span class="string">"editing"</span>);

}

},</pre></div></div>

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<p>If you hit <code>enter</code>, we&#39;re through editing the item.</p>

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<div class="content"><div class='highlight'><pre> updateOnEnter: <span class="keyword">function</span>(e) {

<span class="keyword">if</span> (e.keyCode == <span class="number">13</span>) <span class="keyword">this</span>.close();

},</pre></div></div>

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<p>Remove the item, destroy the model.</p>

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<div class="content"><div class='highlight'><pre> clear: <span class="keyword">function</span>() {

<span class="keyword">this</span>.model.destroy();

}

});</pre></div></div>

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<h2>The Application</h2>

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<p>Our overall <strong>AppView</strong> is the top-level piece of UI.</p>

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<div class="content"><div class='highlight'><pre> <span class="keyword">var</span> AppView = Backbone.View.extend({</pre></div></div>

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<p>Instead of generating a new element, bind to the existing skeleton of

the App already present in the HTML.</p>

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<div class="content"><div class='highlight'><pre> el: $(<span class="string">"#todoapp"</span>),</pre></div></div>

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<p>Our template for the line of statistics at the bottom of the app.</p>

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<div class="content"><div class='highlight'><pre> statsTemplate: _.template($(<span class="string">'#stats-template'</span>).html()),</pre></div></div>

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<p>Delegated events for creating new items, and clearing completed ones.</p>

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<div class="content"><div class='highlight'><pre> events: {

<span class="string">"keypress #new-todo"</span>: <span class="string">"createOnEnter"</span>,

<span class="string">"click #clear-completed"</span>: <span class="string">"clearCompleted"</span>,

<span class="string">"click #toggle-all"</span>: <span class="string">"toggleAllComplete"</span>

},</pre></div></div>

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<p>At initialization we bind to the relevant events on the <code>Todos</code>

collection, when items are added or changed. Kick things off by

loading any preexisting todos that might be saved in <em>localStorage</em>.</p>

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<div class="content"><div class='highlight'><pre> initialize: <span class="keyword">function</span>() {

<span class="keyword">this</span>.input = <span class="keyword">this</span>.$(<span class="string">"#new-todo"</span>);

<span class="keyword">this</span>.allCheckbox = <span class="keyword">this</span>.$(<span class="string">"#toggle-all"</span>)[<span class="number">0</span>];

<span class="keyword">this</span>.listenTo(Todos, <span class="string">'add'</span>, <span class="keyword">this</span>.addOne);

<span class="keyword">this</span>.listenTo(Todos, <span class="string">'reset'</span>, <span class="keyword">this</span>.addAll);

<span class="keyword">this</span>.listenTo(Todos, <span class="string">'all'</span>, <span class="keyword">this</span>.render);

<span class="keyword">this</span>.footer = <span class="keyword">this</span>.$(<span class="string">'footer'</span>);

<span class="keyword">this</span>.main = $(<span class="string">'#main'</span>);

Todos.fetch();

},</pre></div></div>

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<p>Re-rendering the App just means refreshing the statistics -- the rest

of the app doesn&#39;t change.</p>

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<div class="content"><div class='highlight'><pre> render: <span class="keyword">function</span>() {

<span class="keyword">var</span> done = Todos.done().length;

<span class="keyword">var</span> remaining = Todos.remaining().length;

<span class="keyword">if</span> (Todos.length) {

<span class="keyword">this</span>.main.show();

<span class="keyword">this</span>.footer.show();

<span class="keyword">this</span>.footer.html(<span class="keyword">this</span>.statsTemplate({done: done, remaining: remaining}));

} <span class="keyword">else</span> {

<span class="keyword">this</span>.main.hide();

<span class="keyword">this</span>.footer.hide();

}

<span class="keyword">this</span>.allCheckbox.checked = !remaining;

},</pre></div></div>

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<p>Add a single todo item to the list by creating a view for it, and

appending its element to the <code>&lt;ul&gt;</code>.</p>

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<div class="content"><div class='highlight'><pre> addOne: <span class="keyword">function</span>(todo) {

<span class="keyword">var</span> view = <span class="keyword">new</span> TodoView({model: todo});

<span class="keyword">this</span>.$(<span class="string">"#todo-list"</span>).append(view.render().el);

},</pre></div></div>

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<p>Add all items in the <strong>Todos</strong> collection at once.</p>

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<div class="content"><div class='highlight'><pre> addAll: <span class="keyword">function</span>() {

Todos.each(<span class="keyword">this</span>.addOne, <span class="keyword">this</span>);

},</pre></div></div>

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<p>If you hit return in the main input field, create new <strong>Todo</strong> model,

persisting it to <em>localStorage</em>.</p>

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<div class="content"><div class='highlight'><pre> createOnEnter: <span class="keyword">function</span>(e) {

<span class="keyword">if</span> (e.keyCode != <span class="number">13</span>) <span class="keyword">return</span>;

<span class="keyword">if</span> (!<span class="keyword">this</span>.input.val()) <span class="keyword">return</span>;

Todos.create({title: <span class="keyword">this</span>.input.val()});

<span class="keyword">this</span>.input.val(<span class="string">''</span>);

},</pre></div></div>

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<p>Clear all done todo items, destroying their models.</p>

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<div class="content"><div class='highlight'><pre> clearCompleted: <span class="keyword">function</span>() {

_.invoke(Todos.done(), <span class="string">'destroy'</span>);

<span class="keyword">return</span> <span class="literal">false</span>;

},

toggleAllComplete: <span class="function"><span class="keyword">function</span> <span class="params">()</span> {</span>

<span class="keyword">var</span> done = <span class="keyword">this</span>.allCheckbox.checked;

Todos.each(<span class="function"><span class="keyword">function</span> <span class="params">(todo)</span> {</span> todo.save({<span class="string">'done'</span>: done}); });

}

});</pre></div></div>

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<p>Finally, we kick things off by creating the <strong>App</strong>.</p>

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<div class="content"><div class='highlight'><pre> <span class="keyword">var</span> App = <span class="keyword">new</span> AppView;

});</pre></div></div>

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