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Rendr is a small library from Airbnb that allows you to run your Backbone.js apps seamlessly on both the client and the server. Allow your web server to serve fully-formed HTML pages to any deep link of your app, while preserving the snappy feel of a traditional Backbone.js client-side MVC app.

Reporting problems and getting help

Please use the issue tracker to report bugs. For support with using rendr, try asking in the Google group or join #rendr on irc.freenode.org.

Getting Started

To see how to use Rendr to build a simple web app, check out the examples directory for a number of different ways to set up a Rendr app.

Check out the blog post for a more thorough introduction to Rendr.

The Premise

Our hypothesis is that there has to be a better way to build rich web apps today. In the last few years, we've seen more of the application moved to the client-side, with JavaScript representations of views, templates, and models. This can result in interactive, native-style apps, but it also poses challenges. SEO, performance, and maintainability become issues with splitting up your app into two distinct codebases, often in different languages.

The Goals

Rendr is intended to be a building block along the way to this envisionsed future of web apps that can be run on either side of the wire according to the needs of your application.

Some specific design goals:

• Write application logic agnostic to environment
• Minimize if (server) {...} else {...}
• Talk to RESTful API
• Library, not a framework
• Hide complexity in library
• No server-side DOM
• Simple Express middleware

What's Included

Rendr does not attempt to be a fully-fledged, batteries-included application framework. Instead, it follows Backbone's lead by imposing minimal structure, allowing the developer to use the library in the most appropriate way for their application.

Base classes

BaseView

Inherits from Backbone.View.

Public methods

view.postInitialize()

Environment: shared.

This is where you put any initialization logic. We've hijacked the default view.initialize() to do Rendr-specific initialization stuff.

view.preRender()

Environment: shared.

view.render()

Environment: client.

You should never have to override view.render() unless you're doing something really custom. Instead, you should be able to do anything you need using view.postRender(),

view.postRender()

Environment: client.

Here is where you'd put any initialization code that needs to access the DOM. This is a good place for jQuery plugins, sliders, etc.

view.getTemplateData()

Environment: shared.

The default implementation returns something reasonable: essentially view.model.toJSON() or {models: view.collection.toJSON()}. This method is easy to override in order to pass custom data to the template, or to decorate the model data.

var MyView = BaseView.extend({
  getTemplateData: function() {
    // Get `super`.
    var data = BaseView.prototype.getTemplateData.call(this);
    return _.extend({}, data, {
      someOtherProperty: 'something custom'
    });
  }
});

Methods you can override for custom view behaviors

view.getTemplate()

Environment: shared.

You should never need to touch this, unless you're heavily customizing the view. Return a function that gets executed with a single data object as an argument.

view.getTemplateName()

Environment: shared.

You'll probably never touch this unless you're heavily customizing the view. This defaults to view.constructor.id. You can return a string to render a different template. This is used by the default implementation of view.getTemplate().

view.getInnerHtml()

Environment: shared.

view.getHtml()

Environment: shared.

view.getAttributes()

Environment: shared.

Gets HTML attributes for outer DOM element. Used by view.getHtml().

BaseModel

Inherits from Backbone.Model.

BaseCollection

Inherits from Backbone.Collection.

BaseApp

Inherits from Backbone.Model.

BaseAppView

Inherits for BaseView. You can change your main content container from this view by changing the contentEl key in the options object when extending BaseAppView

var AppView = BaseAppView.extend({
  options : {
    contentEl : "#mainContent"
  }
})

BaseRouter

ClientRouter

Inherits from BaseRouter.

ServerRouter

Inherits from BaseRouter.

Express middleware

There are a few middleware functions included. Use some or all of these, or use your own.

initApp

What's Not Included

Express app

Rather than owning your entire Express app, Rendr simply provides some useful middleware that you can mount into your existing Express app.

Asset pipeline

Asset bundling and serving are outside of Rendr's scope. However, it does have some specific requirements for JavaScript packaging to support modules that are accessible in the CommonJS style on both the client and server. The example app uses Stitch for this, though you could also do this with other tools, such as Browserify.

Notes

Rendr uses the native ECMAScript 5 methods Array.prototype.map, Function.prototype.bind, Object.create, etc. If you plan to support older browsers, such as IE<=8, you should include the lovely es5-shim (and es5-sham) libraries as client-side dependencies.

TODO

While we do have it powering a few apps in production here at Airbnb, Rendr is still a prototype. It's a spike; a functional proof-of-concept of a shared client-server architecture based on Backbone. Thus, it carries over a number of design quirks specific to its original use case, and it's not yet very generalized and modular.

Some of the more glaring things to do:

• Support Browserify and streamline module packaging.
• Support templating solutions other than Handlebars.
• Pull out routing code into separate module and share it between client and server, to prevent bugs arising from using Backbone.history to process routes in the client, and Express to process routes on the server.

Contributing

We'd love to see what the community can come up with! There are no doubt a number of developers who are tackling this same problem, and we can learn from each other. If you have a bug fix or feature proposal, submit a pull request with a clear description of the change, plus tests.

Rendr was originally developed by @braitz and @spikebrehm, and now has a healthy list of contributors.

License

MIT