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<body>
<div id="sidebar" class="interface">
<a class="toc_title" href="#">
Backbone.js <span class="version">(0.3.3)</span>
</a>
<a class="toc_title" href="#Introduction">
Introduction
</a>
<a class="toc_title" href="#Events">
Events
</a>
<ul class="toc_section">
<li>– <a href="#Events-bind">bind</a></li>
<li>– <a href="#Events-unbind">unbind</a></li>
<li>– <a href="#Events-trigger">trigger</a></li>
</ul>
<a class="toc_title" href="#Model">
Model
</a>
<ul class="toc_section">
<li>– <a href="#Model-extend">extend</a></li>
<li>– <a href="#Model-constructor">constructor / initialize</a></li>
<li>– <a href="#Model-get">get</a></li>
<li>– <a href="#Model-set">set</a></li>
<li>– <a href="#Model-escape">escape</a></li>
<li>– <a href="#Model-has">has</a></li>
<li>– <a href="#Model-unset">unset</a></li>
<li>– <a href="#Model-clear">clear</a></li>
<li>– <a href="#Model-id">id</a></li>
<li>– <a href="#Model-cid">cid</a></li>
<li>– <a href="#Model-attributes">attributes</a></li>
<li>– <a href="#Model-defaults">defaults</a></li>
<li>- <a href="#Model-toJSON">toJSON</a></li>
<li>– <a href="#Model-fetch">fetch</a></li>
<li>– <a href="#Model-save">save</a></li>
<li>– <a href="#Model-destroy">destroy</a></li>
<li>– <a href="#Model-validate">validate</a></li>
<li>– <a href="#Model-url">url</a></li>
<li>– <a href="#Model-urlRoot">urlRoot</a></li>
<li>– <a href="#Model-parse">parse</a></li>
<li>– <a href="#Model-clone">clone</a></li>
<li>– <a href="#Model-isNew">isNew</a></li>
<li>– <a href="#Model-change">change</a></li>
<li>– <a href="#Model-hasChanged">hasChanged</a></li>
<li>– <a href="#Model-changedAttributes">changedAttributes</a></li>
<li>– <a href="#Model-previous">previous</a></li>
<li>– <a href="#Model-previousAttributes">previousAttributes</a></li>
</ul>
<a class="toc_title" href="#Collection">
Collection
</a>
<ul class="toc_section">
<li>– <a href="#Collection-extend">extend</a></li>
<li>– <a href="#Collection-model">model</a></li>
<li>– <a href="#Collection-constructor">constructor / initialize</a></li>
<li>– <a href="#Collection-models">models</a></li>
<li>– <a href="#Collection-toJSON">toJSON</a></li>
<li>– <a href="#Collection-Underscore-Methods"><b>Underscore Methods (25)</b></a></li>
<li>– <a href="#Collection-add">add</a></li>
<li>– <a href="#Collection-remove">remove</a></li>
<li>– <a href="#Collection-get">get</a></li>
<li>– <a href="#Collection-getByCid">getByCid</a></li>
<li>– <a href="#Collection-at">at</a></li>
<li>– <a href="#Collection-length">length</a></li>
<li>– <a href="#Collection-comparator">comparator</a></li>
<li>– <a href="#Collection-sort">sort</a></li>
<li>– <a href="#Collection-pluck">pluck</a></li>
<li>– <a href="#Collection-url">url</a></li>
<li>– <a href="#Collection-parse">parse</a></li>
<li>– <a href="#Collection-fetch">fetch</a></li>
<li>– <a href="#Collection-reset">reset</a></li>
<li>– <a href="#Collection-create">create</a></li>
</ul>
<a class="toc_title" href="#Router">
Router
</a>
<ul class="toc_section">
<li>– <a href="#Router-extend">extend</a></li>
<li>– <a href="#Router-routes">routes</a></li>
<li>– <a href="#Router-constructor">constructor / initialize</a></li>
<li>– <a href="#Router-route">route</a></li>
<li>– <a href="#Router-saveLocation">saveLocation</a></li>
<li>– <a href="#Router-setLocation">setLocation</a></li>
</ul>
<a class="toc_title" href="#History">
History
</a>
<ul class="toc_section">
<li>– <a href="#History-start">start</a></li>
</ul>
<a class="toc_title" href="#Sync">
Sync
</a>
<ul class="toc_section">
<li>– <a href="#Sync">Backbone.sync</a></li>
<li>– <a href="#Sync-emulateHTTP">Backbone.emulateHTTP</a></li>
<li>– <a href="#Sync-emulateJSON">Backbone.emulateJSON</a></li>
</ul>
<a class="toc_title" href="#View">
View
</a>
<ul class="toc_section">
<li>– <a href="#View-extend">extend</a></li>
<li>– <a href="#View-constructor">constructor / initialize</a></li>
<li>– <a href="#View-el">el</a></li>
<li>– <a href="#View-dollar">$ (jQuery or Zepto)</a></li>
<li>– <a href="#View-render">render</a></li>
<li>– <a href="#View-remove">remove</a></li>
<li>– <a href="#View-make">make</a></li>
<li>– <a href="#View-delegateEvents">delegateEvents</a></li>
</ul>
<a class="toc_title" href="#Utility">
Utility
</a>
<ul class="toc_section">
<li>– <a href="#Utility-noConflict">noConflict</a></li>
</ul>
<a class="toc_title" href="#examples">
Examples
</a>
<ul class="toc_section">
<li>– <a href="#examples-todos">Todos</a></li>
<li>– <a href="#examples-documentcloud">DocumentCloud</a></li>
<li>– <a href="#examples-basecamp">Basecamp Mobile</a></li>
<li>– <a href="#examples-flow">Flow</a></li>
<li>– <a href="#examples-cloudapp">CloudApp</a></li>
<li>– <a href="#examples-soundcloud">Mobile SoundCloud</a></li>
<li>– <a href="#examples-quoteroller">Quote Roller</a></li>
<li>– <a href="#examples-tilemill">TileMill</a></li>
<li>– <a href="#examples-menagerievet">Menagerie Whiteboard</a></li>
<li>- <a href="#examples-instagreat">Insta-great!</a></li>
<li>- <a href="#examples-bittorrent">BitTorrent</a></li>
<li>- <a href="#examples-fluxiom">Fluxiom</a></li>
<li>- <a href="#examples-chop">Chop</a></li>
<li>- <a href="#examples-quietwrite">QuietWrite</a></li>
<li>- <a href="#examples-tzigla">Tzigla</a></li>
<li>- <a href="#examples-substance">Substance</a></li>
</ul>
<a class="toc_title" href="#faq">
F.A.Q.
</a>
<ul class="toc_section">
<li>– <a href="#FAQ-events">Catalog of Events</a></li>
<li>– <a href="#FAQ-nested">Nested Models &amp; Collections</a></li>
<li>– <a href="#FAQ-bootstrap">Loading Bootstrapped Models</a></li>
<li>– <a href="#FAQ-mvc">Traditional MVC</a></li>
<li>– <a href="#FAQ-this">Binding "this"</a></li>
<li>- <a href="#FAQ-rias">Other RIA Frameworks</a></li>
</ul>
<a class="toc_title" href="#changelog">
Change Log
</a>
</div>
<div class="container">
<p>
<img style="width: 385px; height: 126px;" src="docs/images/backbone.png" alt="Backbone.js" />
</p>
<p>
<a href="http://github.com/documentcloud/backbone/">Backbone</a>
supplies structure to JavaScript-heavy applications by providing <b>models</b> with
key-value binding and custom events, <b>collections</b> with a rich API of enumerable functions,
<b>views</b> with declarative event handling, and connects it all to your
existing application over a RESTful JSON interface.
</p>
<p>
The project is <a href="http://github.com/documentcloud/backbone/">hosted on GitHub</a>,
and the <a href="docs/backbone.html">annotated source code</a> is available,
as well as an online <a href="test/test.html">test suite</a>, and
<a href="examples/todos/index.html">example application</a>.
</p>
<p>
You can report bugs and discuss features on the
<a href="http://github.com/documentcloud/backbone/issues">GitHub issues page</a>,
on Freenode IRC in the <tt>#documentcloud</tt> channel, post questions to the
<a href="https://groups.google.com/forum/#!forum/backbonejs">Google Group</a>,
or send tweets to <a href="http://twitter.com/documentcloud">@documentcloud</a>.
</p>
<p>
<i>
Backbone is an open-source component of
<a href="http://documentcloud.org/">DocumentCloud</a>.
</i>
</p>
<h2 id="downloads">
Downloads &amp; Dependencies
<span style="padding-left: 7px; font-size:11px; font-weight: normal;" class="interface">(Right-click, and use "Save As")</span>
</h2>
<table>
<tr>
<td><a href="backbone.js">Development Version (0.3.3)</a></td>
<td><i>35kb, Uncompressed with Comments</i></td>
</tr>
<tr>
<td><a href="backbone-min.js">Production Version (0.3.3)</a></td>
<td><i>3.9kb, Packed and Gzipped</i></td>
</tr>
</table>
<p>
Backbone's only hard dependency is
<a href="http://documentcloud.github.com/underscore/">Underscore.js</a>.
For RESTful persistence, "hashchange" History, and DOM manipulation with
<a href="#View">Backbone.View</a>,
it's highly recommended to include
<a href="https://github.com/douglascrockford/JSON-js">json2.js</a>, and either
<a href="http://jquery.com">jQuery</a> <small>( > 1.4.2)</small> or
<a href="http://zeptojs.com/">Zepto</a>.
</p>
<h2 id="Introduction">Introduction</h2>
<p>
When working on a web application that involves a lot of JavaScript, one
of the first things you learn is to stop tying your data to the DOM. It's all
too easy to create JavaScript applications that end up as tangled piles of
jQuery selectors and callbacks, all trying frantically to keep data in
sync between the HTML UI, your JavaScript logic, and the database on your
server. For rich client-side applications, a more structured approach
is helpful.
</p>
<p>
With Backbone, you represent your data as
<a href="#Model">Models</a>, which can be created, validated, destroyed,
and saved to the server. Whenever a UI action causes an attribute of
a model to change, the model triggers a <i>"change"</i> event; all
the <a href="#View">Views</a> that display the model's data are notified of the
event, causing them to re-render. You don't have to write the glue
code that looks into the DOM to find an element with a specific <i>id</i>,
and update the HTML manually
&mdash; when the model changes, the views simply update themselves.
</p>
<p>
Many of the examples that follow are runnable. Click the <i>play</i> button
to execute them.
</p>
<h2 id="Events">Backbone.Events</h2>
<p>
<b>Events</b> is a module that can be mixed in to any object, giving the
object the ability to bind and trigger custom named events. Events do not
have to be declared before they are bound, and may take passed arguments.
For example:
</p>
<pre class="runnable">
var object = {};
_.extend(object, Backbone.Events);
object.bind("alert", function(msg) {
alert("Triggered " + msg);
});
object.trigger("alert", "an event");
</pre>
<p id="Events-bind">
<b class="header">bind</b><code>object.bind(event, callback)</code>
<br />
Bind a <b>callback</b> function to an object. The callback will be invoked
whenever the <b>event</b> (specified by an arbitrary string identifier) is fired.
If you have a large number of different events on a page, the convention is to use colons to
namespace them: <tt>"poll:start"</tt>, or <tt>"change:selection"</tt>
</p>
<p>
Callbacks bound to the special
<tt>"all"</tt> event will be triggered when any event occurs, and are passed
the name of the event as the first argument. For example, to proxy all events
from one object to another:
</p>
<pre>
proxy.bind("all", function(eventName) {
object.trigger(eventName);
});
</pre>
<p id="Events-unbind">
<b class="header">unbind</b><code>object.unbind([event], [callback])</code>
<br />
Remove a previously-bound <b>callback</b> function from an object. If no
callback is specified, all callbacks for the <b>event</b> will be
removed. If no event is specified, <i>all</i> event callbacks on the object
will be removed.
</p>
<pre>
object.unbind("change", onChange); // Removes just the onChange callback.
object.unbind("change"); // Removes all "change" callbacks.
object.unbind(); // Removes all callbacks on object.
</pre>
<p id="Events-trigger">
<b class="header">trigger</b><code>object.trigger(event, [*args])</code>
<br />
Trigger callbacks for the given <b>event</b>. Subsequent arguments to
<b>trigger</b> will be passed along to the event callbacks.
</p>
<h2 id="Model">Backbone.Model</h2>
<p>
<b>Models</b> are the heart of any JavaScript application, containing
the interactive data as well as a large part of the logic surrounding it:
conversions, validations, computed properties, and access control. You
extend <b>Backbone.Model</b> with your domain-specific methods, and
<b>Model</b> provides a basic set of functionality for managing changes.
</p>
<p>
The following is a contrived example, but it demonstrates defining a model
with a custom method, setting an attribute, and firing an event keyed
to changes in that specific attribute.
After running this code once, <tt>sidebar</tt> will be
available in your browser's console, so you can play around with it.
</p>
<pre class="runnable">
var Sidebar = Backbone.Model.extend({
promptColor: function() {
var cssColor = prompt("Please enter a CSS color:");
this.set({color: cssColor});
}
});
window.sidebar = new Sidebar;
sidebar.bind('change:color', function(model, color) {
$('#sidebar').css({background: color});
});
sidebar.set({color: 'white'});
sidebar.promptColor();
</pre>
<p id="Model-extend">
<b class="header">extend</b><code>Backbone.Model.extend(properties, [classProperties])</code>
<br />
To create a <b>Model</b> class of your own, you extend <b>Backbone.Model</b>
and provide instance <b>properties</b>, as well as optional
<b>classProperties</b> to be attached directly to the constructor function.
</p>
<p>
<b>extend</b> correctly sets up the prototype chain, so subclasses created
with <b>extend</b> can be further extended and subclassed as far as you like.
</p>
<pre>
var Note = Backbone.Model.extend({
initialize: function() { ... },
author: function() { ... },
coordinates: function() { ... },
allowedToEdit: function(account) {
return true;
}
});
var PrivateNote = Note.extend({
allowedToEdit: function(account) {
return account.owns(this);
}
});
</pre>
<p class="warning">
Brief aside on <tt>super</tt>: JavaScript does not provide
a simple way to call super &mdash; the function of the same name defined
higher on the prototype chain. If you override a core function like
<tt>set</tt>, or <tt>save</tt>, and you want to invoke the
parent object's implementation, you'll have to explicitly call it, along these lines:
</p>
<pre>
var Note = Backbone.Model.extend({
set: function(attributes, options) {
Backbone.Model.prototype.set.call(this, attributes, options);
...
}
});
</pre>
<p id="Model-constructor">
<b class="header">constructor / initialize</b><code>new Model([attributes])</code>
<br />
When creating an instance of a model, you can pass in the initial values
of the <b>attributes</b>, which will be <a href="#Model-set">set</a> on the
model. If you define an <b>initialize</b> function, it will be invoked when
the model is created.
</p>
<pre>
new Book({
title: "One Thousand and One Nights",
author: "Scheherazade"
});
</pre>
<p id="Model-get">
<b class="header">get</b><code>model.get(attribute)</code>
<br />
Get the current value of an attribute from the model. For example:
<tt>note.get("title")</tt>
</p>
<p id="Model-set">
<b class="header">set</b><code>model.set(attributes, [options])</code>
<br />
Set a hash of attributes (one or many) on the model. If any of the attributes
change the models state, a <tt>"change"</tt> event will be triggered, unless
<tt>{silent: true}</tt> is passed as an option. Change events for specific
attributes are also triggered, and you can bind to those as well, for example:
<tt>change:title</tt>, and <tt>change:content</tt>.
</p>
<pre>
note.set({title: "October 12", content: "Lorem Ipsum Dolor Sit Amet..."});
</pre>
<p>
If the model has a <a href="#Model-validate">validate</a> method,
it will be validated before the attributes are set, no changes will
occur if the validation fails, and <b>set</b> will return <tt>false</tt>.
You may also pass an <tt>error</tt>
callback in the options, which will be invoked instead of triggering an
<tt>"error"</tt> event, should validation fail.
</p>
<p id="Model-escape">
<b class="header">escape</b><code>model.escape(attribute)</code>
<br />
Similar to <a href="#Model-get">get</a>, but returns the HTML-escaped version
of a model's attribute. If you're interpolating data from the model into
HTML, using <b>escape</b> to retrieve attributes will prevent
<a href="http://en.wikipedia.org/wiki/Cross-site_scripting">XSS</a> attacks.
</p>
<pre class="runnable">
var hacker = new Backbone.Model({
name: "&lt;script&gt;alert('xss')&lt;/script&gt;"
});
alert(hacker.escape('name'));
</pre>
<p id="Model-has">
<b class="header">has</b><code>model.has(attribute)</code>
<br />
Returns <tt>true</tt> if the attribute is set to a non-null or non-undefined
value.
</p>
<pre>
if (note.has("title")) {
...
}
</pre>
<p id="Model-unset">
<b class="header">unset</b><code>model.unset(attribute, [options])</code>
<br />
Remove an attribute by deleting it from the internal attributes hash.
Fires a <tt>"change"</tt> event unless <tt>silent</tt> is passed as an option.
</p>
<p id="Model-clear">
<b class="header">clear</b><code>model.clear([options])</code>
<br />
Removes all attributes from the model. Fires a <tt>"change"</tt> event unless
<tt>silent</tt> is passed as an option.
</p>
<p id="Model-id">
<b class="header">id</b><code>model.id</code>
<br />
A special property of models, the <b>id</b> is an arbitrary string
(integer id or UUID). If you set the <b>id</b> in the
attributes hash, it will be copied onto the model as a direct property.
Models can be retrieved by id from collections, and the id is used to generate
model URLs by default.
</p>
<p id="Model-cid">
<b class="header">cid</b><code>model.cid</code>
<br />
A special property of models, the <b>cid</b> or client id is a unique identifier
automatically assigned to all models when they're first created. Client ids
are handy when the model has not yet been saved to the server, and does not
yet have its eventual true <b>id</b>, but already needs to be visible in the UI.
Client ids take the form: <tt>c1, c2, c3 ...</tt>
</p>
<p id="Model-attributes">
<b class="header">attributes</b><code>model.attributes</code>
<br />
The <b>attributes</b> property is the internal hash containing the model's
state. Please use <a href="#Model-set">set</a> to update the attributes instead of modifying
them directly. If you'd like to retrieve and munge a copy of the model's
attributes, use <a href="#Model-toJSON">toJSON</a> instead.
</p>
<p id="Model-defaults">
<b class="header">defaults</b><code>model.defaults or model.defaults()</code>
<br />
The <b>defaults</b> hash (or function) can be used to specify the default
attributes for your model. When creating an instance of the model,
any unspecified attributes will be set to their default value.
</p>
<pre class="runnable">
var Meal = Backbone.Model.extend({
defaults: {
"appetizer": "caesar salad",
"entree": "ravioli",
"dessert": "cheesecake"
}
});
alert("Dessert will be " + (new Meal).get('dessert'));
</pre>
<p class="warning">
Remember that in JavaScript, objects are passed by reference, so if you
include an object as a default value, it will be shared among all instances.
</p>
<p id="Model-toJSON">
<b class="header">toJSON</b><code>model.toJSON()</code>
<br />
Return a copy of the model's <a href="#Model-attributes">attributes</a> for JSON stringification.
This can be used for persistence, serialization, or for augmentation before
being handed off to a view. The name of this method is a bit confusing, as
it doesn't actually return a JSON string &mdash; but I'm afraid that it's
the way that the <a href="https://developer.mozilla.org/en/JSON#toJSON()_method">JavaScript API for <b>JSON.stringify</b> works</a>.
</p>
<pre class="runnable">
var artist = new Backbone.Model({
firstName: "Wassily",
lastName: "Kandinsky"
});
artist.set({birthday: "December 16, 1866"});
alert(JSON.stringify(artist));
</pre>
<p id="Model-fetch">
<b class="header">fetch</b><code>model.fetch([options])</code>
<br />
Refreshes the model's state from the server. Useful if the model has never
been populated with data, or if you'd like to ensure that you have the
latest server state. A <tt>"change"</tt> event will be triggered if the
server's state differs from the current attributes. Accepts
<tt>success</tt> and <tt>error</tt> callbacks in the options hash, which
are passed <tt>(model, response)</tt> as arguments.
</p>
<pre>
// Poll every 10 seconds to keep the channel model up-to-date.
setInterval(function() {
channel.fetch();
}, 10000);
</pre>
<p id="Model-save">
<b class="header">save</b><code>model.save([attributes], [options])</code>
<br />
Save a model to your database (or alternative persistence layer),
by delegating to <a href="#Sync">Backbone.sync</a>. The <b>attributes</b>
hash (as in <a href="#Model-set">set</a>) should contain the attributes
you'd like to change -- keys that aren't mentioned won't be altered.
If the model has a <a href="#Model-validate">validate</a>
method, and validation fails, the model will not be saved. If the model
<a href="#Model-isNew">isNew</a>, the save will be a <tt>"create"</tt>
(HTTP <tt>POST</tt>), if the model already
exists on the server, the save will be an <tt>"update"</tt> (HTTP <tt>PUT</tt>).
</p>
<p>
In the following example, notice how because the model has never been
saved previously, our overridden version of <tt>Backbone.sync</tt> receives a <tt>"create"</tt> request.
</p>
<pre class="runnable">
Backbone.sync = function(method, model) {
alert(method + ": " + JSON.stringify(model));
};
var book = new Backbone.Model({
title: "The Rough Riders",
author: "Theodore Roosevelt"
});
book.save();
</pre>
<p>
<b>save</b> accepts <tt>success</tt> and <tt>error</tt> callbacks in the
options hash, which are passed <tt>(model, response)</tt> as arguments.
The <tt>error</tt> callback will also be invoked if the model has a
<tt>validate</tt> method, and validation fails. If a server-side
validation fails, return a non-<tt>200</tt> HTTP response code, along with
an error response in text or JSON.
</p>
<pre>
book.save({author: "F.D.R."}, {error: function(){ ... }});
</pre>
<p id="Model-destroy">
<b class="header">destroy</b><code>model.destroy([options])</code>
<br />
Destroys the model on the server by delegating an HTTP <tt>DELETE</tt>
request to <a href="#Sync">Backbone.sync</a>. Accepts
<tt>success</tt> and <tt>error</tt> callbacks in the options hash.
Triggers a <tt>"destroy"</tt> event on the model, which will bubble up
through any collections that contain it.
</p>
<pre>
book.destroy({success: function(model, response) {
...
}});
</pre>
<p id="Model-validate">
<b class="header">validate</b><code>model.validate(attributes)</code>
<br />
This method is left undefined, and you're encouraged to override it with
your custom validation logic, if you have any that can be performed
in JavaScript. <b>validate</b> is called before <tt>set</tt> and
<tt>save</tt>, and is passed the attributes that are about to be updated.
If the model and attributes are valid, don't return anything from <b>validate</b>;
if the attributes are invalid, return an error of your choosing. It
can be as simple as a string error message to be displayed, or a complete
error object that describes the error programmatically. <tt>set</tt> and
<tt>save</tt> will not continue if <b>validate</b> returns an error.
Failed validations trigger an <tt>"error"</tt> event.
</p>
<pre class="runnable">
var Chapter = Backbone.Model.extend({
validate: function(attrs) {
if (attrs.end < attrs.start) {
return "can't end before it starts";
}
}
});
var one = new Chapter({
title : "Chapter One: The Beginning"
});
one.bind("error", function(model, error) {
alert(model.get("title") + " " + error);
});
one.set({
start: 15,
end: 10
});
</pre>
<p>
<tt>"error"</tt> events are useful for providing coarse-grained error
messages at the model or collection level, but if you have a specific view
that can better handle the error, you may override and suppress the event
by passing an <tt>error</tt> callback directly:
</p>
<pre>
account.set({access: "unlimited"}, {
error: function(model, error) {
alert(error);
}
});
</pre>
<p id="Model-url">
<b class="header">url</b><code>model.url()</code>
<br />
Returns the relative URL where the model's resource would be located on
the server. If your models are located somewhere else, override this method
with the correct logic. Generates URLs of the form: <tt>"/[collection.url]/[id]"</tt>,
falling back to <tt>"/[urlRoot]/id"</tt> if the model is not part of a collection.
</p>
<p>
Delegates to <a href="#Collection-url">Collection#url</a> to generate the
URL, so make sure that you have it defined, or a <a href="#Model-urlRoot">urlRoot</a>
property, if all models of this class share a common root URL.
A model with an id of <tt>101</tt>, stored in a
<a href="#Collection">Backbone.Collection</a> with a <tt>url</tt> of <tt>"/documents/7/notes"</tt>,
would have this URL: <tt>"/documents/7/notes/101"</tt>
</p>
<p id="Model-urlRoot">
<b class="header">urlRoot</b><code>model.urlRoot</code>
<br />
Specify a <tt>urlRoot</tt> if you're using a model outside of a collection,
to enable the default <a href="#Model-url">url</a> function to generate
URLs based on the model id. <tt>"/[urlRoot]/id"</tt>
</p>
<pre class="runnable">
var Book = Backbone.Model.extend({urlRoot : '/books'});
var solaris = new Book({id: "1083-lem-solaris"});
alert(solaris.url());
</pre>
<p id="Model-parse">
<b class="header">parse</b><code>model.parse(response)</code>
<br />
<b>parse</b> is called whenever a model's data is returned by the
server, in <a href="#Model-fetch">fetch</a>, and <a href="#Model-save">save</a>.
The function is passed the raw <tt>response</tt> object, and should return
the attributes hash to be <a href="#Model-set">set</a> on the model. The
default implementation is a no-op, simply passing through the JSON response.
Override this if you need to work with a preexisting API, or better namespace
your responses.
</p>
<p>
If you're working with a Rails backend, you'll notice that Rails' default
<tt>to_json</tt> implementation includes a model's attributes under a
namespace. To disable this behavior for seamless Backbone integration, set:
</p>
<pre>
ActiveRecord::Base.include_root_in_json = false
</pre>
<p id="Model-clone">
<b class="header">clone</b><code>model.clone()</code>
<br />
Returns a new instance of the model with identical attributes.
</p>
<p id="Model-isNew">
<b class="header">isNew</b><code>model.isNew()</code>
<br />
Has this model been saved to the server yet? If the model does not yet have
an <tt>id</tt>, it is considered to be new.
</p>
<p id="Model-change">
<b class="header">change</b><code>model.change()</code>
<br />
Manually trigger the <tt>"change"</tt> event.
If you've been passing <tt>{silent: true}</tt> to the <a href="#Model-set">set</a> function in order to
aggregate rapid changes to a model, you'll want to call <tt>model.change()</tt>
when you're all finished.
</p>
<p id="Model-hasChanged">
<b class="header">hasChanged</b><code>model.hasChanged([attribute])</code>
<br />
Has the model changed since the last <tt>"change"</tt> event? If an <b>attribute</b>
is passed, returns <tt>true</tt> if that specific attribute has changed.
</p>
<p class="warning">
Note that this method, and the following change-related ones,
are only useful during the course of a <tt>"change"</tt> event.
</p>
<pre>
book.bind("change", function() {
if (book.hasChanged("title")) {
...
}
});
</pre>
<p id="Model-changedAttributes">
<b class="header">changedAttributes</b><code>model.changedAttributes([attributes])</code>
<br />
Retrieve a hash of only the model's attributes that have changed. Optionally,
an external <b>attributes</b> hash can be passed in, returning
the attributes in that hash which differ from the model. This can be used
to figure out which portions of a view should be updated, or what calls
need to be made to sync the changes to the server.
</p>
<p id="Model-previous">
<b class="header">previous</b><code>model.previous(attribute)</code>
<br />
During a <tt>"change"</tt> event, this method can be used to get the
previous value of a changed attribute.
</p>
<pre class="runnable">
var bill = new Backbone.Model({
name: "Bill Smith"
});
bill.bind("change:name", function(model, name) {
alert("Changed name from " + bill.previous("name") + " to " + name);
});
bill.set({name : "Bill Jones"});
</pre>
<p id="Model-previousAttributes">
<b class="header">previousAttributes</b><code>model.previousAttributes()</code>
<br />
Return a copy of the model's previous attributes. Useful for getting a
diff between versions of a model, or getting back to a valid state after
an error occurs.
</p>
<h2 id="Collection">Backbone.Collection</h2>
<p>
Collections are ordered sets of models. You can to bind <tt>"change"</tt> events
to be notified when any model in the collection has been modified,
listen for <tt>"add"</tt> and <tt>"remove"</tt> events, <tt>fetch</tt>
the collection from the server, and use a full suite of
<a href="#Collection-Underscore-Methods">Underscore.js methods</a>.
</p>
<p>
Any event that is triggered on a model in a collection will also be
triggered on the collection directly, for convenience.
This allows you to listen for changes to specific attributes in any
model in a collection, for example:
<tt>Documents.bind("change:selected", ...)</tt>
</p>
<p id="Collection-extend">
<b class="header">extend</b><code>Backbone.Collection.extend(properties, [classProperties])</code>
<br />
To create a <b>Collection</b> class of your own, extend <b>Backbone.Collection</b>,
providing instance <b>properties</b>, as well as optional <b>classProperties</b> to be attached
directly to the collection's constructor function.
</p>
<p id="Collection-model">
<b class="header">model</b><code>collection.model</code>
<br />
Override this property to specify the model class that the collection
contains. If defined, you can pass raw attributes objects (and arrays) to
<a href="#Collection-add">add</a>, <a href="#Collection-create">create</a>,
and <a href="#Collection-reset">reset</a>, and the attributes will be
converted into a model of the proper type.
</p>
<pre>
var Library = Backbone.Collection.extend({
model: Book
});
</pre>
<p id="Collection-constructor">
<b class="header">constructor / initialize</b><code>new Collection([models], [options])</code>
<br />
When creating a Collection, you may choose to pass in the initial array of <b>models</b>.
The collection's <a href="#Collection-comparator">comparator</a> function
may be included as an option. If you define an <b>initialize</b> function, it will be
invoked when the collection is created.
</p>
<pre>
var tabs = new TabSet([tab1, tab2, tab3]);
</pre>
<p id="Collection-models">
<b class="header">models</b><code>collection.models</code>
<br />
Raw access to the JavaScript array of models inside of the collection. Usually you'll
want to use <tt>get</tt>, <tt>at</tt>, or the <b>Underscore methods</b>
to access model objects, but occasionally a direct reference to the array
is desired.
</p>
<p id="Collection-toJSON">
<b class="header">toJSON</b><code>collection.toJSON()</code>
<br />
Return an array containing the attributes hash of each model in the
collection. This can be used to serialize and persist the
collection as a whole. The name of this method is a bit confusing, because
it conforms to
<a href="https://developer.mozilla.org/en/JSON#toJSON()_method">JavaScript's JSON API</a>.
</p>
<pre class="runnable">
var collection = new Backbone.Collection([
{name: "Tim", age: 5},
{name: "Ida", age: 26},
{name: "Rob", age: 55}
]);
alert(JSON.stringify(collection));
</pre>
<p id="Collection-Underscore-Methods">
<b class="header">Underscore Methods (25)</b>
<br />
Backbone proxies to <b>Underscore.js</b> to provide 25 iteration functions
on <b>Backbone.Collection</b>. They aren't all documented here, but
you can take a look at the Underscore documentation for the full details&hellip;
</p>
<ul>
<li><a href="http://documentcloud.github.com/underscore/#each">forEach (each)</a></li>
<li><a href="http://documentcloud.github.com/underscore/#map">map</a></li>
<li><a href="http://documentcloud.github.com/underscore/#reduce">reduce (foldl, inject)</a></li>
<li><a href="http://documentcloud.github.com/underscore/#reduceRight">reduceRight (foldr)</a></li>
<li><a href="http://documentcloud.github.com/underscore/#detect">find (detect)</a></li>
<li><a href="http://documentcloud.github.com/underscore/#select">filter (select)</a></li>
<li><a href="http://documentcloud.github.com/underscore/#reject">reject</a></li>
<li><a href="http://documentcloud.github.com/underscore/#all">every (all)</a></li>
<li><a href="http://documentcloud.github.com/underscore/#any">some (any)</a></li>
<li><a href="http://documentcloud.github.com/underscore/#include">include</a></li>
<li><a href="http://documentcloud.github.com/underscore/#invoke">invoke</a></li>
<li><a href="http://documentcloud.github.com/underscore/#max">max</a></li>
<li><a href="http://documentcloud.github.com/underscore/#min">min</a></li>
<li><a href="http://documentcloud.github.com/underscore/#sortBy">sortBy</a></li>
<li><a href="http://documentcloud.github.com/underscore/#sortedIndex">sortedIndex</a></li>
<li><a href="http://documentcloud.github.com/underscore/#toArray">toArray</a></li>
<li><a href="http://documentcloud.github.com/underscore/#size">size</a></li>
<li><a href="http://documentcloud.github.com/underscore/#first">first</a></li>
<li><a href="http://documentcloud.github.com/underscore/#rest">rest</a></li>
<li><a href="http://documentcloud.github.com/underscore/#last">last</a></li>
<li><a href="http://documentcloud.github.com/underscore/#without">without</a></li>
<li><a href="http://documentcloud.github.com/underscore/#indexOf">indexOf</a></li>
<li><a href="http://documentcloud.github.com/underscore/#lastIndexOf">lastIndexOf</a></li>
<li><a href="http://documentcloud.github.com/underscore/#isEmpty">isEmpty</a></li>
<li><a href="http://documentcloud.github.com/underscore/#chain">chain</a></li>
</ul>
<pre>
Books.each(function(book) {
book.publish();
});
var titles = Books.map(function(book) {
return book.get("title");
});
var publishedBooks = Books.filter(function(book) {
return book.get("published") === true;
});
var alphabetical = Books.sortBy(function(book) {
return book.author.get("name").toLowerCase();
});
</pre>
<p id="Collection-add">
<b class="header">add</b><code>collection.add(models, [options])</code>
<br />
Add a model (or an array of models) to the collection. Fires an <tt>"add"</tt>
event, which you can pass <tt>{silent: true}</tt> to suppress. If a
<a href="#Collection-model">model</a> property is defined, you may also pass
raw attributes objects, and have them be vivified as instances of the model.
Pass <tt>{at: index}</tt> to splice the model into the collection at the
specified <tt>index</tt>.
</p>
<pre class="runnable">
var ships = new Backbone.Collection;
ships.bind("add", function(ship) {
alert("Ahoy " + ship.get("name") + "!");
});
ships.add([
{name: "Flying Dutchman"},
{name: "Black Pearl"}
]);
</pre>
<p id="Collection-remove">
<b class="header">remove</b><code>collection.remove(models, [options])</code>
<br />
Remove a model (or an array of models) from the collection. Fires a
<tt>"remove"</tt> event, which you can use <tt>silent</tt>
to suppress.
</p>
<p id="Collection-get">
<b class="header">get</b><code>collection.get(id)</code>
<br />
Get a model from a collection, specified by <b>id</b>.
</p>
<pre>
var book = Library.get(110);
</pre>
<p id="Collection-getByCid">
<b class="header">getByCid</b><code>collection.getByCid(cid)</code>
<br />
Get a model from a collection, specified by client id. The client id
is the <tt>.cid</tt> property of the model, automatically assigned whenever
a model is created. Useful for models which have not yet been saved to
the server, and do not yet have true ids.
</p>
<p id="Collection-at">
<b class="header">at</b><code>collection.at(index)</code>
<br />
Get a model from a collection, specified by index. Useful if your collection
is sorted, and if your collection isn't sorted, <b>at</b> will still
retrieve models in insertion order.
</p>
<p id="Collection-length">
<b class="header">length</b><code>collection.length</code>
<br />
Like an array, a Collection maintains a <tt>length</tt> property, counting
the number of models it contains.
</p>
<p id="Collection-comparator">
<b class="header">comparator</b><code>collection.comparator</code>
<br />
By default there is no <b>comparator</b> function on a collection.
If you define a comparator, it will be used to maintain
the collection in sorted order. This means that as models are added,
they are inserted at the correct index in <tt>collection.models</tt>.
Comparator functions take a model and return a numeric or string value
by which the model should be ordered relative to others.
</p>
<p>
Note how even though all of the chapters in this example are added backwards,
they come out in the proper order:
</p>
<pre class="runnable">
var Chapter = Backbone.Model;
var chapters = new Backbone.Collection;
chapters.comparator = function(chapter) {
return chapter.get("page");
};
chapters.add(new Chapter({page: 9, title: "The End"}));
chapters.add(new Chapter({page: 5, title: "The Middle"}));
chapters.add(new Chapter({page: 1, title: "The Beginning"}));
alert(chapters.pluck('title'));
</pre>
<p class="warning">
Brief aside: This comparator function is different than JavaScript's regular
"sort", which must return <tt>0</tt>, <tt>1</tt>, or <tt>-1</tt>,
and is more similar to a <tt>sortBy</tt> &mdash; a much nicer API.
</p>
<p id="Collection-sort">
<b class="header">sort</b><code>collection.sort([options])</code>
<br />
Force a collection to re-sort itself. You don't need to call this under
normal circumstances, as a collection with a <a href="#Collection-comparator">comparator</a> function
will maintain itself in proper sort order at all times. Calling <b>sort</b>
triggers the collection's <tt>"reset"</tt> event, unless silenced by passing
<tt>{silent: true}</tt>
</p>
<p id="Collection-pluck">
<b class="header">pluck</b><code>collection.pluck(attribute)</code>
<br />
Pluck an attribute from each model in the collection. Equivalent to calling
<tt>map</tt>, and returning a single attribute from the iterator.
</p>
<pre class="runnable">
var stooges = new Backbone.Collection([
new Backbone.Model({name: "Curly"}),
new Backbone.Model({name: "Larry"}),
new Backbone.Model({name: "Moe"})
]);
var names = stooges.pluck("name");
alert(JSON.stringify(names));
</pre>
<p id="Collection-url">
<b class="header">url</b><code>collection.url or collection.url()</code>
<br />
Set the <b>url</b> property (or function) on a collection to reference
its location on the server. Models within the collection will use <b>url</b>
to construct URLs of their own.
</p>
<pre>
var Notes = Backbone.Collection.extend({
url: '/notes'
});
// Or, something more sophisticated:
var Notes = Backbone.Collection.extend({
url: function() {
return this.document.url() + '/notes';
}
});
</pre>
<p id="Collection-parse">
<b class="header">parse</b><code>collection.parse(response)</code>
<br />
<b>parse</b> is called by Backbone whenever a collection's models are
returned by the server, in <a href="#Collection-fetch">fetch</a>.
The function is passed the raw <tt>response</tt> object, and should return
the array of model attributes to be <a href="#Collection-add">added</a>
to the collection. The default implementation is a no-op, simply passing
through the JSON response. Override this if you need to work with a
preexisting API, or better namespace your responses.
</p>
<pre>
var Tweets = Backbone.Collection.extend({
// The Twitter Search API returns tweets under "results".
parse: function(response) {
return response.results;
}
});
</pre>
<p id="Collection-fetch">
<b class="header">fetch</b><code>collection.fetch([options])</code>
<br />
Fetch the default set of models for this collection from the server,
refreshing the collection when they arrive. The <b>options</b> hash takes
<tt>success</tt> and <tt>error</tt>
callbacks which will be passed <tt>(collection, response)</tt> as arguments.
When the model data returns from the server, the collection will
<a href="#Collection-reset">reset</a>.
Delegates to <a href="#Sync">Backbone.sync</a>
under the covers, for custom persistence strategies.
The server handler for <b>fetch</b> requests should return a JSON array of
models.
</p>
<pre class="runnable">
Backbone.sync = function(method, model) {
alert(method + ": " + model.url);
};
var Accounts = new Backbone.Collection;
Accounts.url = '/accounts';
Accounts.fetch();
</pre>
<p>
If you'd like to add the incoming models to the current collection, instead
of replacing the collection's contents, pass <tt>{add: true}</tt> as an
option to <b>fetch</b>.
</p>
<p>
<b>jQuery.ajax</b> options can also be passed directly as <b>fetch</b> options,
so to fetch a specific page of a paginated collection:
<tt>Documents.fetch({data: {page: 3}})</tt>
</p>
<p>
Note that <b>fetch</b> should not be used to populate collections on
page load &mdash; all models needed at load time should already be
<a href="#FAQ-bootstrap">bootstrapped</a> in to place. <b>fetch</b> is
intended for lazily-loading models for interfaces that are not needed
immediately: for example, documents with collections of notes that may be
toggled open and closed.
</p>
<p id="Collection-reset">
<b class="header">reset</b><code>collection.reset(models, [options])</code>
<br />
Adding and removing models one at a time is all well and good, but sometimes
you have so many models to change that you'd rather just update the collection
in bulk. Use <b>reset</b> to replace a collection with a new list
of models (or attribute hashes), triggering a single <tt>"reset"</tt> event
at the end. Pass <tt>{silent: true}</tt> to suppress the <tt>"reset"</tt> event.
Using reset with no arguments is useful as a way to empty the collection.
</p>
<p>
Here's an example using <b>reset</b> to bootstrap a collection during initial page load,
in a Rails application.
</p>
<pre>
&lt;script&gt;
Accounts.reset(&lt;%= @accounts.to_json %&gt;);
&lt;/script&gt;
</pre>
<p>
Calling <tt>collection.reset()</tt> without passing any models as arguments
will empty the entire collection.
</p>
<p id="Collection-create">
<b class="header">create</b><code>collection.create(attributes, [options])</code>
<br />
Convenience to create a new instance of a model within a collection.
Equivalent to instantiating a model with a hash of attributes,
saving the model to the server, and adding the model to the set after being
successfully created. Returns
the model, or <tt>false</tt> if a validation error prevented the
model from being created. In order for this to work, your should set the
<a href="#Collection-model">model</a> property of the collection.
The <b>create</b> method can accept either an attributes hash or an
existing, unsaved model object.
</p>
<pre>
var Library = Backbone.Collection.extend({
model: Book
});
var NYPL = new Library;
var othello = NYPL.create({
title: "Othello",
author: "William Shakespeare"
});
</pre>
<h2 id="Router">Backbone.Router</h2>
<p>
Web applications often choose to change their URL fragment (<tt>#fragment</tt>)
in order to provide shareable, bookmarkable URLs for an Ajax-heavy application.
<b>Backbone.Router</b> provides methods for routing client-side URL
fragments, and connecting them to actions and events.
</p>
<p>
During page load, after your application has finished creating all of its routers,
be sure to call <tt>Backbone.history.start()</tt>, or
<tt>Backbone.history.start({pushState: true})</tt> to route the initial URL.
</p>
<p id="Router-extend">
<b class="header">extend</b><code>Backbone.Router.extend(properties, [classProperties])</code>
<br />
Get started by creating a custom router class. You'll
want to define actions that are triggered when certain URL fragments are
matched, and provide a <a href="#Router-routes">routes</a> hash
that pairs routes to actions.
</p>
<pre>
var Workspace = Backbone.Router.extend({
routes: {
"help": "help", // #help
"search/:query": "search", // #search/kiwis
"search/:query/p:page": "search" // #search/kiwis/p7
},
help: function() {
...
},
search: function(query, page) {
...
}
});
</pre>
<p id="Router-routes">
<b class="header">routes</b><code>router.routes</code>
<br />
The routes hash maps URLs with parameters to functions on your router,
similar to the <a href="#View">View</a>'s <a href="#View-delegateEvents">events hash</a>.
Routes can contain parameter parts, <tt>:param</tt>, which match a single URL
component between slashes; and splat parts <tt>*splat</tt>, which can match
any number of URL components.
</p>
<p>
For example, a route of <tt>"search/:query/p:page"</tt> will match
a fragment of <tt>#search/obama/p2</tt>, passing <tt>"obama"</tt>
and <tt>"2"</tt> to the action. A route of <tt>"file/*path"</tt> will
match <tt>#file/nested/folder/file.txt</tt>,
passing <tt>"nested/folder/file.txt"</tt> to the action.
</p>
<p>
When the visitor presses the back button, or enters a URL, and a particular
route is matched, the name of the action will be fired as an
<a href="#Events">event</a>, so that other objects can listen to the router,
and be notified. In the following example, visiting <tt>#help/uploading</tt>
will fire a <tt>route:help</tt> event from the router.
</p>
<pre>
routes: {
"help/:page": "help",
"download/*path": "download",
"folder/:name": "openFolder",
"folder/:name-:mode": "openFolder"
}
</pre>
<pre>
router.bind("route:help", function(page) {
...
});
</pre>
<p id="Router-constructor">
<b class="header">constructor / initialize</b><code>new Router([options])</code>
<br />
When creating a new router, you may pass its
<a href="#Router-routes">routes</a> hash directly as an option, if you
choose. All <tt>options</tt> will also be passed to your <tt>initialize</tt>
function, if defined.
</p>
<p id="Router-route">
<b class="header">route</b><code>router.route(route, name, callback)</code>
<br />
Manually create a route for the router, The <tt>route</tt> argument may
be a <a href="#Router-routes">routing string</a> or regular expression.
Each matching capture from the route or regular expression will be passed as
an argument to the callback. The <tt>name</tt> argument will be triggered as
a <tt>"route:name"</tt> event whenever the route is matched.
</p>
<pre>
initialize: function(options) {
// Matches #page/10, passing "10"
this.route("page/:number", "page", function(number){ ... });
// Matches /117-a/b/c/open, passing "117-a/b/c"
this.route(/^(.*?)\/open$/, "open", function(id){ ... });
}
</pre>
<p id="Router-saveLocation">
<b class="header">saveLocation</b><code>router.saveLocation(fragment)</code>
<br />
Whenever you reach a point in your application that you'd like to save
as a URL, call <b>saveLocation</b> in order to update the URL fragment
without triggering a <tt>hashchange</tt> event. (If you would prefer to
trigger the event and routing, you can just set the hash directly.)
</p>
<pre>
openPage: function(pageNumber) {
this.document.pages.at(pageNumber).open();
this.saveLocation("page/" + pageNumber);
}
</pre>
<p id="Router-setLocation">
<b class="header">setLocation</b><code>router.setLocation(fragment)</code>
<br />
Just like <a href="#Router-saveLocation">saveLocation</a>, but also triggers
your route action at the same time. Useful if you want to transition to a page
where no state serialization is necessary, like a simple string.
</p>
<pre>
app.setLocation("help/troubleshooting");
</pre>
<h2 id="History">Backbone.history</h2>
<p>
<b>History</b> serves as a global router (per frame) to handle <tt>hashchange</tt>
events, match the appropriate route, and trigger callbacks. You shouldn't
ever have to create one of these yourself &mdash; you should use the reference
to <tt>Backbone.history</tt> that will be created for you automatically if you make use
of <a href="#Router">Routers</a> with <a href="#Router-routes">routes</a>.
</p>
<p id="History-start">
<b class="header">start</b><code>Backbone.history.start()</code>
<br />
When all of your <a href="#Router">Routers</a> have been created,
and all of the routes are set up properly, call <tt>Backbone.history.start()</tt>
to begin monitoring <tt>hashchange</tt> events, and dispatching routes.
</p>
<p>
When called, if a route succeeds with a match for the current URL,
<tt>Backbone.history.start()</tt> returns <tt>true</tt>. If no defined
routes matches the current URL fragment, it returns <tt>false</tt>.
</p>
<pre>
$(function(){
new WorkspaceRouter();
new HelpPaneRouter();
Backbone.history.start();
});
</pre>
<h2 id="Sync">Backbone.sync</h2>
<p>
<b>Backbone.sync</b> is the function the Backbone calls every time it
attempts to read or save a model to the server. By default, it uses
<tt>(jQuery/Zepto).ajax</tt> to make a RESTful JSON request. You can override
it in order to use a different persistence strategy, such as WebSockets,
XML transport, or Local Storage.
</p>
<p>
The method signature of <b>Backbone.sync</b> is <tt>sync(method, model, success, error)</tt>
</p>
<ul>
<li><b>method</b> – the CRUD method (<tt>"create"</tt>, <tt>"read"</tt>, <tt>"update"</tt>, or <tt>"delete"</tt>)</li>
<li><b>model</b> – the model to be saved (or collection to be read)</li>
<li><b>success({model: ...})</b> – a callback that should be fired if the request works</li>
<li><b>error({model: ...})</b> – a callback that should be fired if the request fails</li>
</ul>
<p>
With the default implementation, when <b>Backbone.sync</b> sends up a request to save
a model, its attributes will be passed, serialized as JSON, and sent in the HTTP body
with content-type <tt>application/json</tt>. When returning a JSON response,
send down the attributes of the model that have been changed by the server, and need
to be updated on the client. When responding to a <tt>"read"</tt> request from a collection
(<a href="#Collection#fetch">Collection#fetch</a>), send down an array
of model attribute objects.
</p>
<p>
The default <b>sync</b> handler maps CRUD to REST like so:
</p>
<ul>
<li><b>create &rarr; POST &nbsp; </b><tt>/collection</tt></li>
<li><b>read &rarr; GET &nbsp; </b><tt>/collection[/id]</tt></li>
<li><b>update &rarr; PUT &nbsp; </b><tt>/collection/id</tt></li>
<li><b>delete &rarr; DELETE &nbsp; </b><tt>/collection/id</tt></li>
</ul>
<p>
As an example, a Rails handler responding to an <tt>"update"</tt> call from
<tt>Backbone</tt> might look like this: <i>(In real code, never use
</i><tt>update_attributes</tt><i> blindly, and always whitelist the attributes
you allow to be changed.)</i>
</p>
<pre>
def update
account = Account.find params[:id]
account.update_attributes params
render :json => account
end
</pre>
<p>
One more tip for Rails integration is to disable the default namespacing for
<tt>to_json</tt> calls on models by setting <tt>ActiveRecord::Base.include_root_in_json = false</tt>
</p>
<p id="Sync-emulateHTTP">
<b class="header">emulateHTTP</b><code>Backbone.emulateHTTP = true</code>
<br />
If you want to work with a legacy web server that doesn't support Backbones's
default REST/HTTP approach, you may choose to turn on <tt>Backbone.emulateHTTP</tt>.
Setting this option will fake <tt>PUT</tt> and <tt>DELETE</tt> requests with
a HTTP <tt>POST</tt>, and pass them under the <tt>_method</tt> parameter. Setting this option
will also set an <tt>X-HTTP-Method-Override</tt> header with the true method.
</p>
<pre>
Backbone.emulateHTTP = true;
model.save(); // POST to "/collection/id", with "_method=PUT" + header.
</pre>
<p id="Sync-emulateJSON">
<b class="header">emulateJSON</b><code>Backbone.emulateJSON = true</code>
<br />
If you're working with a legacy web server that can't handle requests
encoded as <tt>application/json</tt>, setting <tt>Backbone.emulateJSON = true;</tt>
will cause the JSON to be serialized under a <tt>model</tt> parameter, and
the request to be made with a <tt>application/x-www-form-urlencoded</tt>
mime type, as if from an HTML form.
</p>
<h2 id="View">Backbone.View</h2>
<p>
Backbone views are almost more convention than they are code &mdash; they
don't determine anything about your HTML or CSS for you, and can be used
with any JavaScript templating library.
The general idea is to organize your interface into logical views,
backed by models, each of which can be updated independently when the
model changes, without having to redraw the page. Instead of digging into
a JSON object, looking up an element in the DOM, and updating the HTML by hand,
you can bind your view's <tt>render</tt> function to the model's <tt>"change"</tt>
event &mdash; and now everywhere that
model data is displayed in the UI, it is always immediately up to date.
</p>
<p id="View-extend">
<b class="header">extend</b><code>Backbone.View.extend(properties, [classProperties])</code>
<br />
Get started with views by creating a custom view class. You'll want to
override the <a href="#View-render">render</a> function, specify your
declarative <a href="#View-delegateEvents">events</a>, and perhaps the
<tt>tagName</tt>, <tt>className</tt>, or <tt>id</tt> of the View's root
element.
</p>
<pre>
var DocumentRow = Backbone.View.extend({
tagName: "li",
className: "document-row",
events: {
"click .icon": "open",
"click .button.edit": "openEditDialog",
"click .button.delete": "destroy"
},
initialize: function() {
_.bindAll(this, "render");
},
render: function() {
...
}
});
</pre>
<p id="View-constructor">
<b class="header">constructor / initialize</b><code>new View([options])</code>
<br />
When creating a new View, the options you pass are attached to the view
as <tt>this.options</tt>, for future reference. There are several special
options that, if passed, will be attached directly to the view:
<tt>model</tt>, <tt>collection</tt>,
<tt>el</tt>, <tt>id</tt>, <tt>className</tt>, and <tt>tagName</tt>.
If the view defines an <b>initialize</b> function, it will be called when
the view is first created. If you'd like to create a view that references
an element <i>already</i> in the DOM, pass in the element as an option:
<tt>new View({el: existingElement})</tt>
</p>
<pre>
var doc = Documents.first();
new DocumentRow({
model: doc,
id: "document-row-" + doc.id
});
</pre>
<p id="View-el">
<b class="header">el</b><code>view.el</code>
<br />
All views have a DOM element at all times (the <b>el</b> property),
whether they've already been inserted into the page or not. In this
fashion, views can be rendered at any time, and inserted into the DOM all
at once, in order to get high-performance UI rendering with as few
reflows and repaints as possible. <tt>this.el</tt> is created from the
view's <tt>tagName</tt>, <tt>className</tt>, and <tt>id</tt> properties,
if specified. If not, <b>el</b> is an empty <tt>div</tt>.
</p>
<p>
You may assign <b>el</b> directly if the view is being
created for an element that already exists in the DOM. Use either a
reference to a real DOM element, or a css selector string.
</p>
<pre class="runnable">
var ItemView = Backbone.View.extend({
tagName: 'li'
});
var BodyView = Backbone.View.extend({
el: 'body'
});
var item = new ItemView();
var body = new BodyView();
alert(item.el + ' ' + body.el);
</pre>
<p id="View-dollar">
<b class="header">$ (jQuery or Zepto)</b><code>view.$(selector)</code>
<br />
If jQuery or Zepto is included on the page, each view has a
<b>$</b> function that runs queries scoped within the view's element. If you use this
scoped jQuery function, you don't have to use model ids as part of your query
to pull out specific elements in a list, and can rely much more on HTML class
attributes. It's equivalent to running: <tt>$(selector, this.el)</tt>
</p>
<pre>
ui.Chapter = Backbone.View.extend({
serialize : function() {
return {
title: this.$(".title").text(),
start: this.$(".start-page").text(),
end: this.$(".end-page").text()
};
}
});
</pre>
<p id="View-render">
<b class="header">render</b><code>view.render()</code>
<br />
The default implementation of <b>render</b> is a no-op. Override this
function with your code that renders the view template from model data,
and updates <tt>this.el</tt> with the new HTML. A good
convention is to <tt>return this</tt> at the end of <b>render</b> to
enable chained calls.
</p>
<pre>
var Bookmark = Backbone.View.extend({
render: function() {
$(this.el).html(this.template(this.model.toJSON()));
return this;
}
});
</pre>
<p>
Backbone is agnostic with respect to your preferred method of HTML templating.
Your <b>render</b> function could even munge together an HTML string, or use
<tt>document.createElement</tt> to generate a DOM tree. However, we suggest
choosing a nice JavaScript templating library.
<a href="http://github.com/janl/mustache.js">Mustache.js</a>,
<a href="http://github.com/creationix/haml-js">Haml-js</a>, and
<a href="http://github.com/sstephenson/eco">Eco</a> are all fine alternatives.
Because <a href="http://documentcloud.github.com/underscore/">Underscore.js</a> is already on the page,
<a href="http://documentcloud.github.com/underscore/#template">_.template</a>
is available, and is an excellent choice if you've already XSS-sanitized
your interpolated data.
</p>
<p>
Whatever templating strategy you end up with, it's nice if you <i>never</i>
have to put strings of HTML in your JavaScript. At DocumentCloud, we
use <a href="http://documentcloud.github.com/jammit/">Jammit</a> in order
to package up JavaScript templates stored in <tt>/app/views</tt> as part
of our main <tt>core.js</tt> asset package.
</p>
<p id="View-remove">
<b class="header">remove</b><code>view.remove()</code>
<br />
Convenience function for removing the view from the DOM. Equivalent to calling
<tt>$(view.el).remove();</tt>
</p>
<p id="View-make">
<b class="header">make</b><code>view.make(tagName, [attributes], [content])</code>
<br />
Convenience function for creating a DOM element of the given type (<b>tagName</b>),
with optional attributes and HTML content. Used internally to create the
initial <tt>view.el</tt>.
</p>
<pre class="runnable">
var view = new Backbone.View;
var el = view.make("b", {className: "bold"}, "Bold! ");
$("#make-demo").append(el);
</pre>
<div id="make-demo"></div>
<p id="View-delegateEvents">
<b class="header">delegateEvents</b><code>delegateEvents([events])</code>
<br />
Uses jQuery's <tt>delegate</tt> function to provide declarative callbacks
for DOM events within a view.
If an <b>events</b> hash is not passed directly, uses <tt>this.events</tt>
as the source. Events are written in the format <tt>{"event selector": "callback"}</tt>.
Omitting the <tt>selector</tt> causes the event to be bound to the view's
root element (<tt>this.el</tt>). By default, <tt>delegateEvents</tt> is called
within the View's constructor for you, so if you have a simple <tt>events</tt>
hash, all of your DOM events will always already be connected, and you will
never have to call this function yourself.
</p>
<p>
Using <b>delegateEvents</b> provides a number of advantages over manually
using jQuery to bind events to child elements during <a href="#View-render">render</a>. All attached
callbacks are bound to the view before being handed off to jQuery, so when
the callbacks are invoked, <tt>this</tt> continues to refer to the view object. When
<b>delegateEvents</b> is run again, perhaps with a different <tt>events</tt>
hash, all callbacks are removed and delegated afresh &mdash; useful for
views which need to behave differently when in different modes.
</p>
<p>
A view that displays a document in a search result might look
something like this:
</p>
<pre>
var DocumentView = Backbone.View.extend({
events: {
"dblclick" : "open",
"click .icon.doc" : "select",
"contextmenu .icon.doc" : "showMenu",
"click .show_notes" : "toggleNotes",
"click .title .lock" : "editAccessLevel",
"mouseover .title .date" : "showTooltip"
},
render: function() {
$(this.el).html(this.template(this.model.toJSON()));
return this;
},
open: function() {
window.open(this.model.get("viewer_url"));
},
select: function() {
this.model.set({selected: true});
},
...
});
</pre>
<h2 id="Utility">Utility Functions</h2>
<p>
</p>
<p id="Utility-noConflict">
<b class="header">noConflict</b><code>var backbone = Backbone.noConflict();</code>
<br />
Returns the <tt>Backbone</tt> object back to its original value. You can
use the return value of <tt>Backbone.noConflict()</tt> to keep a local
reference to Backbone. Useful for embedding Backbone on third-party
websites, where you don't want to clobber the existing Backbone.
</p>
<pre>
var localBackbone = Backbone.noConflict();
var model = localBackbone.Model.extend(...);
</pre>
<h2 id="examples">Examples</h2>
<p id="examples-todos">
<a href="http://jgn.me/">Jérôme Gravel-Niquet</a> has contributed a
<a href="examples/todos/index.html">Todo List application</a>
that is bundled in the repository as Backbone example. If you're wondering
where to get started with Backbone in general, take a moment to
<a href="docs/todos.html">read through the annotated source</a>. The app uses a
<a href="docs/backbone-localstorage.html">LocalStorage adapter</a>
to transparently save all of your todos within your browser, instead of
sending them to a server. Jérôme also has a version hosted at
<a href="http://localtodos.com/">localtodos.com</a> that uses a
<a href="http://github.com/jeromegn/backbone-mootools">MooTools-backed version of Backbone</a>
instead of jQuery.
</p>
<div style="text-align: center;">
<a href="examples/todos/index.html">
<img src="docs/images/todos.png" alt="Todos" class="example_image" />
</a>
</div>
<h2 id="examples-documentcloud">DocumentCloud</h2>
<p>
The <a href="http://www.documentcloud.org/public/#search/">DocumentCloud workspace</a>
is built on Backbone.js, with <i>Documents</i>, <i>Projects</i>,
<i>Notes</i>, and <i>Accounts</i> all as Backbone models and collections.
If you're interested in history &mdash; both Underscore.js and Backbone.js
were originally extracted from the DocumentCloud codebase, and packaged
into standalone JS libraries.
</p>
<div style="text-align: center;">
<a href="http://www.documentcloud.org/public/#search/">
<img src="docs/images/dc-workspace.png" alt="DocumentCloud Workspace" class="example_image" />
</a>
</div>
<h2 id="examples-basecamp">Basecamp Mobile</h2>
<p>
<a href="http://37signals.com/">37Signals</a> used Backbone.js to create
<a href="http://basecamphq.com/mobile">Basecamp Mobile</a>, the mobile version
of their popular project management software. You can access all your Basecamp
projects, post new messages, and comment on milestones (all represented
internally as Backbone.js models).
</p>
<div style="text-align: center;">
<a href="http://basecamphq.com/mobile">
<img src="docs/images/basecamp-mobile.png" alt="Basecamp Mobile" class="example_image" />
</a>
</div>
<h2 id="examples-flow">Flow</h2>
<p>
<a href="http://www.metalabdesign.com/">MetaLab</a> used Backbone.js to create
<a href="http://www.getflow.com/">Flow</a>, a task management app for teams. The
workspace relies on Backbone.js to construct task views, activities, accounts,
folders, projects, and tags. You can see the internals under <tt>window.Flow</tt>.
</p>
<div style="text-align: center;">
<a href="http://www.getflow.com/">
<img src="docs/images/flow.png" alt="Flow" class="example_image" />
</a>
</div>
<h2 id="examples-cloudapp">CloudApp</h2>
<p>
<a href="http://getcloudapp.com">CloudApp</a> is simple file and link
sharing for the Mac. Backbone.js powers the web tools
which consume the <a href="http://developer.getcloudapp.com">documented API</a>
to manage Drops. Data is either pulled manually or pushed by
<a href="http://pusher.com">Pusher</a> and fed to
<a href="http://github.com/janl/mustache.js">Mustache</a> templates for
rendering. Check out the <a href="http://cloudapp.github.com/engine">annotated source code</a>
to see the magic.
</p>
<div style="text-align: center;">
<a href="http://getcloudapp.com">
<img src="docs/images/cloudapp.png" alt="CloudApp" class="example_image" />
</a>
</div>
<h2 id="examples-soundcloud">SoundCloud</h2>
<p>
<a href="http://soundcloud.com">SoundCloud</a> is the leading sound sharing
platform on the internet, and Backbone.js provides the foundation for
<a href="http://m.soundcloud.com">Mobile SoundCloud</a>. The project uses
the public SoundCloud <a href="http://soundcloud.com/developers">API</a>
as a data source (channeled through a nginx proxy),
<a href="http://api.jquery.com/category/plugins/templates/">jQuery templates</a>
for the rendering, <a href="http://docs.jquery.com/Qunit">Qunit
</a> and <a href="http://code.google.com/p/phantomjs/">PhantomJS</a> for
the testing suite. The JS code, templates and CSS are built for the
production deployment with various Node.js tools like
<a href="https://github.com/dsimard/ready.js">ready.js</a>,
<a href="https://github.com/mde/node-jake">Jake</a>,
<a href="https://github.com/tmpvar/jsdom">jsdom</a>.
The <b>Backbone.History</b> was modified to support the HTML5 <tt>history.pushState</tt>.
<b>Backbone.sync</b> was extended with an additional SessionStorage based cache
layer.
</p>
<div style="text-align: center;">
<a href="http://m.soundcloud.com">
<img src="docs/images/soundcloud.png" alt="SoundCloud" class="example_image" />
</a>
</div>
<h2 id="examples-quoteroller">Quote Roller</h2>
<p>
<a href="http://www.codingstaff.com">Coding Staff</a> used Backbone.js to
create <a href="http://www.quoteroller.com">Quote Roller</a>, an application
that helps to create, send, organize and track business proposals with ease.
Backbone.js has been used to implement interactive parts of the
application like template builder, pricing table, file attachments manager.
</p>
<div style="text-align: center;">
<a href="http://www.quoteroller.com">
<img src="docs/images/quoteroller.png" alt="Quote Roller" class="example_image" />
</a>
</div>
<h2 id="examples-tilemill">TileMill</h2>
<p>
Our fellow
<a href="http://www.newschallenge.org/">Knight Foundation News Challenge</a>
winners, <a href="http://mapbox.com/">MapBox</a>, created an open-source
map design studio with Backbone.js:
<a href="http://mapbox.github.com/tilemill/">TileMill</a>.
TileMill lets you manage map layers based on shapefiles and rasters, and
edit their appearance directly in the browser with the
<a href="https://github.com/mapbox/carto">Carto styling language</a>.
Note that the gorgeous <a href="http://mapbox.com/">MapBox</a> homepage
is also a Backbone.js app.
</p>
<div style="text-align: center;">
<a href="http://mapbox.github.com/tilemill/">
<img src="docs/images/tilemill.png" alt="TileMill" class="example_image" />
</a>
</div>
<h2 id="examples-menagerievet">Menagerie Whiteboard</h2>
<p>
<a href="http://twitter.com/_aaron_">Aaron Hamid</a> and
<a href="http://twitter.com/mkuklis">Michal Kuklis</a> from
<a href="http://incandescentsoftware.com">Incandescent Software</a>
used Backbone.js to create
<a href="http://menagerievet.com">Menagerie Whiteboard</a> a digital
"whiteboard" for veterinary practices. Backbone <b>Models</b> were used to
sync the data with CouchDB. A Backbone <b>Controller</b> was used for
routing and bookmarkable deep links. Backbone <b>Views</b> were used to
bind, listen and 'react' to changes coming from models.
<b>Backbone.sync</b> was extended to support connection to CouchDB
and deployment as a CouchApp.
</p>
<div style="text-align: center;">
<a href="http://menagerievet.com/">
<img src="docs/images/menagerievet.png" alt="MenagerieVet" class="example_image" />
</a>
</div>
<h2 id="examples-instagreat">Insta-great!</h2>
<p>
<a href="http://twitter.com/elliottkember">Elliott Kember</a> and
<a href="http://twitter.com/dizzyup">Hector Simpson</a> built
<a href="http://instagre.at">Insta-great!</a>
- a fun way to explore popular photos and interact with
<a href="http://instagram.com/">Instagram</a> on the web.
Elliott says, "Backbone.js and Coffeescript were insanely useful for
writing clean, consistent UI code and keeping everything modular and
readable, even through several code refactors. I'm in love."
</p>
<div style="text-align: center;">
<a href="http://instagre.at">
<img src="docs/images/instagreat.png" alt="instagre.at" class="example_image" />
</a>
</div>
<h2 id="examples-bittorrent">BitTorrent</h2>
<p>
<a href="http://www.bittorrent.com">BitTorrent</a> used Backbone to
completely rework an existing Win32 UI. Models normalize access to the
client's data and views rely heavily on the <tt>change</tt> events to keep
the UI state current. Using Backbone and SCSS,
<a href="http://www.bittorrent.com/chrysalis/">our new design</a> and UX
prototypes are considerably easier to iterate, test and work with than
the original Win32 UI.
</p>
<div style="text-align: center;">
<a href="http://www.bittorrent.com/chrysalis/">
<img src="docs/images/bittorrent.jpg" alt="BitTorrent" class="example_image" />
</a>
</div>
<h2 id="examples-fluxiom">Fluxiom</h2>
<p>
<a href="http://fluxiom.com">Fluxiom</a> uses Backbone.js and HTML5 to
deliver a seamless upload experience from the desktop to the cloud,
including drag and drop, live previews, partial uploads, and one-click sharing.
<p>
<p>
The upload queue is a single collection and each file is it’s own model.
The UI is divided into several views for efficient event handling, and
uses <a href="http://documentcloud.github.com/underscore/">Underscore.js</a>
templates for fast rendering, even when handling hundreds of uploads.
</p>
<div style="text-align: center;">
<a href="http://fluxiom.com/">
<img src="docs/images/fluxiom.png" alt="Fluxiom" class="example_image" />
</a>
</div>
<h2 id="examples-chop">Chop</h2>
<p>
<a href="http://chopapp.com/">Chop</a> is a little app from
<a href="http://www.zurb.com/">ZURB</a> that lets people slice up bad code
and share their feedback to help put it back together.
Chop was built to demonstrate how easy it is to build pageless apps
using Backbone.js and Rails. Chop makes extensive use of Backbone <b>Views</b>,
<b>Controllers</b>, and <b>Models</b>.
</p>
<div style="text-align: center;">
<a href="http://chopapp.com/">
<img src="docs/images/chop.png" alt="Chop" class="example_image" />
</a>
</div>
<h2 id="examples-quietwrite">QuietWrite</h2>
<p>
<a href="http://www.twitter.com/jamesjyu">James Yu</a> used Backbone.js to
create <a href="http://www.quietwrite.com/">QuietWrite</a>, an app
that gives writers a clean and quiet interface to concentrate on the text itself.
The editor relies on Backbone to persist document data to the server. He
followed up with a Backbone.js + Rails tutorial that describes how to implement
<a href="http://www.jamesyu.org/2011/01/27/cloudedit-a-backbone-js-tutorial-by-example/">CloudEdit, a simple document editing app</a>.
</p>
<div style="text-align: center;">
<a href="http://www.quietwrite.com/">
<img src="docs/images/quietwrite.png" alt="QuietWrite" class="example_image" />
</a>
</div>
<h2 id="examples-tzigla">Tzigla</h2>
<p>
<a href="http://twitter.com/evilchelu">Cristi Balan</a> and
<a href="http://dira.ro">Irina Dumitrascu</a> created
<a href="http://tzigla.com">Tzigla</a>, a collaborative drawing
application where artists make tiles that connect to each other to
create <a href="http://tzigla.com/boards/1">surreal drawings</a>.
Backbone models help organize the code, routers provide
<a href="http://tzigla.com/boards/1#!/tiles/2-2">bookmarkable deep links</a>,
and the views are rendered with
<a href="https://github.com/creationix/haml-js">haml.js</a> and
<a href="http://zeptojs.com/">Zepto</a>.
Tzigla is written in Ruby (Rails) on the backend, and
<a href="http://coffeescript.org">CoffeeScript</a> on the frontend, with
<a href="http://documentcloud.github.com/jammit/">Jammit</a>
prepackaging the static assets.
</p>
<div style="text-align: center;">
<a href="http://www.tzigla.com/">
<img src="docs/images/tzigla.png" alt="Tzigla" class="example_image" />
</a>
</div>
<h2 id="examples-substance">Substance</h2>
<p>
Michael Aufreiter is building an open source document authoring and
publishing engine: <a href="http://substance.io">Substance</a>.
Substance makes use of Backbone.View and Backbone.Router, while
Backbone plays well together with
<a href="http://github.com/michael/data">Data.js</a>, which is used for
data persistence.
</p>
<div style="text-align: center;">
<a href="http://substance.io/">
<img src="docs/images/substance.png" alt="Substance" class="example_image" />
</a>
</div>
<h2 id="faq">F.A.Q.</h2>
<p id="FAQ-events">
<b class="header">Catalog of Events</b>
<br />
Here's a list of all of the built-in events that Backbone.js can fire.
You're also free to trigger your own events on Models and Views as you
see fit.
</p>
<ul>
<li><b>"add"</b> (model, collection) &mdash; when a model is added to a collection. </li>
<li><b>"remove"</b> (model, collection) &mdash; when a model is removed from a collection. </li>
<li><b>"reset"</b> (collection) &mdash; when the collection's entire contents have been replaced. </li>
<li><b>"change"</b> (model, collection) &mdash; when a model's attributes have changed. </li>
<li><b>"change:[attribute]"</b> (model, collection) &mdash; when a specific attribute has been updated. </li>
<li><b>"destrooy"</b> (model, collection) &mdash; when a model is <a href="#Model-destroy">destroyed</a>. </li>
<li><b>"error"</b> (model, collection) &mdash; when a model's validation fails, or a <a href="#Model-save">save</a> call fails on the server. </li>
<li><b>"route:[name]"</b> (router) &mdash; when one of a router's routes has matched. </li>
<li><b>"all"</b> &mdash; this special event fires for <i>any</i> triggered event, passing the event name as the first argument. </li>
</ul>
<p id="FAQ-nested">
<b class="header">Nested Models &amp; Collections</b>
<br />
It's common to nest collections inside of models with Backbone. For example,
consider a <tt>Mailbox</tt> model that contains many <tt>Message</tt> models.
One nice pattern for handling this is have a <tt>this.messages</tt> collection
for each mailbox, enabling the lazy-loading of messages, when the mailbox
is first opened ... perhaps with <tt>MessageList</tt> views listening for
<tt>"add"</tt> and <tt>"remove"</tt> events.
</p>
<pre>
var Mailbox = Backbone.Model.extend({
initialize: function() {
this.messages = new Messages;
this.messages.url = '/mailbox/' + this.id + '/messages';
this.messages.bind("reset", this.updateCounts);
},
...
});
var Inbox = new Mailbox;
// And then, when the Inbox is opened:
Inbox.messages.fetch();
</pre>
<p id="FAQ-bootstrap">
<b class="header">Loading Bootstrapped Models</b>
<br />
When your app first loads, it's common to have a set of initial models that
you know you're going to need, in order to render the page. Instead of
firing an extra AJAX request to <a href="#Collection-fetch">fetch</a> them,
a nicer pattern is to have their data already bootstrapped into the page.
You can then use <a href="#Collection-reset">reset</a> to populate your
collections with the initial data. At DocumentCloud, in the
<a href="http://en.wikipedia.org/wiki/ERuby">ERB</a> template for the
workspace, we do something along these lines:
</p>
<pre>
&lt;script&gt;
Accounts.reset(&lt;%= @accounts.to_json %&gt;);
Projects.reset(&lt;%= @projects.to_json(:collaborators => true) %&gt;);
&lt;/script&gt;
</pre>
<p id="FAQ-mvc">
<b class="header">How does Backbone relate to "traditional" MVC?</b>
<br />
Different implementations of the
<a href="http://en.wikipedia.org/wiki/Model–View–Controller">Model-View-Controller</a>
pattern tend to disagree about the definition of a controller. If it helps any, in
Backbone, the <a href="#View">View</a> class can also be thought of as a
kind of controller, dispatching events that originate from the UI, with
the HTML template serving as the true view. We call it a View because it
represents a logical chunk of UI, responsible for the contents of a single
DOM element.
</p>
<p>
Comparing the overall structure of Backbone to a server-side MVC framework
like <b>Rails</b>, the pieces line up like so:
</p>
<ul>
<li>
<b>Backbone.Model</b> &ndash; Like a Rails model minus the class
methods. Wraps a row of data in business logic.
</li>
<li>
<b>Backbone.Collection</b> &ndash; A group of models on the client-side,
with sorting/filtering/aggregation logic.
</li>
<li>
<b>Backbone.Router</b> &ndash; Rails <tt>routes.rb</tt> + Rails controller
actions. Maps URLs to functions.
</li>
<li>
<b>Backbone.View</b> &ndash; A logical, re-usable piece of UI. Often,
but not always, associated with a model.
</li>
<li>
<b>Client-side Templates</b> &ndash; Rails <tt>.html.erb</tt> views,
rendering a chunk of HTML.
</li>
</ul>
<p id="FAQ-this">
<b class="header">Binding "this"</b>
<br />
Perhaps the single most common JavaScript "gotcha" is the fact that when
you pass a function as a callback, it's value for <tt>this</tt> is lost. With
Backbone, when dealing with <a href="#Events">events</a> and callbacks,
you'll often find it useful to rely on
<a href="http://documentcloud.github.com/underscore/#bind">_.bind</a> and
<a href="http://documentcloud.github.com/underscore/#bindAll">_.bindAll</a>
from Underscore.js. <tt>_.bind</tt> takes a function and an object to be
used as <tt>this</tt>, any time the function is called in the future.
<tt>_.bindAll</tt> takes an object and a list of method names: each method
in the list will be bound to the object, so that it's <tt>this</tt> may
not change. For example, in a <a href="#View">View</a> that listens for
changes to a collection...
</p>
<pre>
var MessageList = Backbone.View.extend({
initialize: function() {
_.bindAll(this, "addMessage", "removeMessage", "render");
var messages = this.collection;
messages.bind("reset", this.render);
messages.bind("add", this.addMessage);
messages.bind("remove", this.removeMessage);
}
});
// Later, in the app...
Inbox.messages.add(newMessage);
</pre>
<p id="FAQ-rias">
<b class="header">
How is Backbone different than
<a href="http://www.sproutcore.com/">SproutCore</a> or
<a href="http://cappuccino.org/">Cappuccino</a>?
</b>
<br />
This question is frequently asked, and all three projects apply general
<a href="http://en.wikipedia.org/wiki/Model–View–Controller">Model-View-Controller</a>
principles to JavaScript applications. However, there isn't much basis
for comparison. SproutCore and Cappuccino provide rich UI widgets, vast
core libraries, and determine the structure of your HTML for you.
Both frameworks measure in the hundreds of kilobytes when packed and
gzipped, and megabytes of JavaScript, CSS, and images when loaded in the browser
&mdash; there's a lot of room underneath for libraries of a more moderate scope.
Backbone is a <i>4 kilobyte</i> include that provides
just the core concepts of models, events, collections, views, controllers,
and persistence.
</p>
<h2 id="changelog">Change Log</h2>
<p>
<b class="header">0.4.0</b> &mdash; <small><i>FUTURE DATE, 2011</i></small><br />
<tt>Collection.refresh</tt> renamed to <tt>Collection.reset</tt> to emphasize
its ability to both refresh the collection with new models, as well as empty
out the collection when used with no parameters.
</p>
<p>
<b class="header">0.3.3</b> &mdash; <small><i>Dec 1, 2010</i></small><br />
Backbone.js now supports <a href="http://zeptojs.com">Zepto</a>, alongside
jQuery, as a framework for DOM manipulation and Ajax support.
Implemented <a href="#Model-escape">Model#escape</a>, to efficiently handle
attributes intended for HTML interpolation. When trying to persist a model,
failed requests will now trigger an <tt>"error"</tt> event. The
ubiquitous <tt>options</tt> argument is now passed as the final argument
to all <tt>"change"</tt> events.
</p>
<p>
<b class="header">0.3.2</b> &mdash; <small><i>Nov 23, 2010</i></small><br />
Bugfix for IE7 + iframe-based "hashchange" events. <tt>sync</tt> may now be
overridden on a per-model, or per-collection basis. Fixed recursion error
when calling <tt>save</tt> with no changed attributes, within a
<tt>"change"</tt> event.
</p>
<p>
<b class="header">0.3.1</b> &mdash; <small><i>Nov 15, 2010</i></small><br />
All <tt>"add"</tt> and <tt>"remove"</tt> events are now sent through the
model, so that views can listen for them without having to know about the
collection. Added a <tt>remove</tt> method to <a href="#View">Backbone.View</a>.
<tt>toJSON</tt> is no longer called at all for <tt>'read'</tt> and <tt>'delete'</tt> requests.
Backbone routes are now able to load empty URL fragments.
</p>
<p>
<b class="header">0.3.0</b> &mdash; <small><i>Nov 9, 2010</i></small><br />
Backbone now has <a href="#Controller">Controllers</a> and
<a href="#History">History</a>, for doing client-side routing based on
URL fragments.
Added <tt>emulateHTTP</tt> to provide support for legacy servers that don't
do <tt>PUT</tt> and <tt>DELETE</tt>.
Added <tt>emulateJSON</tt> for servers that can't accept <tt>application/json</tt>
encoded requests.
Added <a href="#Model-clear">Model#clear</a>, which removes all attributes
from a model.
All Backbone classes may now be seamlessly inherited by CoffeeScript classes.
</p>
<p>
<b class="header">0.2.0</b> &mdash; <small><i>Oct 25, 2010</i></small><br />
Instead of requiring server responses to be namespaced under a <tt>model</tt>
key, now you can define your own <a href="#Model-parse">parse</a> method
to convert responses into attributes for Models and Collections.
The old <tt>handleEvents</tt> function is now named
<a href="#View-delegateEvents">delegateEvents</a>, and is automatically
called as part of the View's constructor.
Added a <a href="#Collection-toJSON">toJSON</a> function to Collections.
Added <a href="#Collection-chain">Underscore's chain</a> to Collections.
</p>
<p>
<b class="header">0.1.2</b> &mdash; <small><i>Oct 19, 2010</i></small><br />
Added a <a href="#Model-fetch">Model#fetch</a> method for refreshing the
attributes of single model from the server.
An <tt>error</tt> callback may now be passed to <tt>set</tt> and <tt>save</tt>
as an option, which will be invoked if validation fails, overriding the
<tt>"error"</tt> event.
You can now tell backbone to use the <tt>_method</tt> hack instead of HTTP
methods by setting <tt>Backbone.emulateHTTP = true</tt>.
Existing Model and Collection data is no longer sent up unnecessarily with
<tt>GET</tt> and <tt>DELETE</tt> requests. Added a <tt>rake lint</tt> task.
Backbone is now published as an <a href="http://npmjs.org">NPM</a> module.
</p>
<p>
<b class="header">0.1.1</b> &mdash; <small><i>Oct 14, 2010</i></small><br />
Added a convention for <tt>initialize</tt> functions to be called
upon instance construction, if defined. Documentation tweaks.
</p>
<p>
<b class="header">0.1.0</b> &mdash; <small><i>Oct 13, 2010</i></small><br />
Initial Backbone release.
</p>
<p>
<br />
<a href="http://documentcloud.org/" title="A DocumentCloud Project" style="background:none;">
<img src="http://jashkenas.s3.amazonaws.com/images/a_documentcloud_project.png" alt="A DocumentCloud Project" style="position:relative;left:-10px;" />
</a>
</p>
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