Recently two Khan Academy devs dropped into our team chat and said they were gonna use React to write a new feature. They even hinted that we may want to adopt it product-wide.
"The library is only a week old. It's a brand new way of thinking about things. We're the first to use it outside of Facebook. Heck, even the React devs were surprised to hear we're using this in production!!!"
Over the past several weeks, members of our team, Pete Hunt and Paul O'Shannessy, answered many questions that were asked in the React group. They give a good overview of how to integrate React with other libraries and APIs through the use of Mixins and Lifecycle Methods.
JSFiddle: Basically I've given you two mixins. The first lets you react to global scroll events. The second is, IMO, much more useful: it gives you scroll start and scroll end events, which you can use with setState() to create components that react based on whether the user is scrolling or not.
Gist: The big thing to notice is that my component is pretty dumb (it doesn't have to be but that's how I chose to model it). All it does is render itself based on the props that are passed in. renderOrUpdate is where the "magic" happens.
Gist: This example is doing everything -- including the IO -- inside of a single React component.
Gist: One pattern that we use at Instagram a lot is to employ separation of concerns and consolidate I/O and state into components higher in the hierarchy to keep the rest of the components mostly stateless and purely display.
JSFiddle: Your React component simply render empty divs, and then in componentDidMount() you call React.renderComponent() on each of those divs to set up a new root React tree. Be sure to explicitly unmountAndReleaseReactRootNode() for each component in componentWillUnmount().
React v0.4 is very close to completion. As we finish it off, we'd like to share with you some of the major changes we've made since v0.3. This is the first of several posts we'll be making over the next week.
If you take a look at most of our current examples, you'll see us using React.autoBind for event handlers. This is used in place of Function.prototype.bind. Remember that in JS, function calls are late-bound. That means that if you simply pass a function around, the this used inside won't necessarily be the this you expect. Function.prototype.bind creates a new, properly bound, function so that when called, this is exactly what you expect it to be.
Before we launched React, we would write this:
React.createClass({onClick:function(event){/* do something with this */},render:function(){return<buttononClick={this.onClick.bind(this)}/>;}});
We wrote React.autoBind as a way to cache the function creation and save on memory usage. Since render can get called multiple times, if you used this.onClick.bind(this) you would actually create a new function on each pass. With React v0.3 you were able to write this instead:
React.createClass({onClick:React.autoBind(function(event){/* do something with this */}),render:function(){return<buttononClick={this.onClick}/>;}});
After using React.autoBind for a few weeks, we realized that there were very few times that we didn't want that behavior. So we made it the default! Now all methods defined within React.createClass will already be bound to the correct instance.
Starting with v0.4 you can just write this:
React.createClass({onClick:function(event){/* do something with this */},render:function(){return<buttononClick={this.onClick}/>;}});
For v0.4 we will simply be making React.autoBind a no-op — it will just return the function you pass to it. Most likely you won't have to change your code to account for this change, though we encourage you to update. We'll publish a migration guide documenting this and other changes that come along with React v0.4.
Clay Allsopp successfully ported Propeller, a fairly big, interaction-heavy JavaScript app, to React.
Subviews involve a lot of easy-to-forget boilerplate that Backbone (by design) doesn't automate. Libraries like Backbone.Marionette offer more abstractions to make view nesting easier, but they're all limited by the fact that Backbone delegates how and went view-document attachment occurs to the application code.
React, on the other hand, manages the DOM and only exposes real nodes at select points in its API. The "elements" you code in React are actually objects which wrap DOM nodes, not the actual objects which get inserted into the DOM. Internally, React converts those abstractions into actual DOMElements and fills out the document accordingly. [...]
We moved about 20 different Backbone view classes to React over the past few weeks, including the live-preview pane that you see in our little iOS demo. Most importantly, it's allowed us to put energy into making each component work great on its own, instead of spending extra cycles to ensure they function in unison. For that reason, we think React is a more scalable way to build view-intensive apps than Backbone alone, and it doesn't require you to drop-everything-and-refactor like a move to Ember or Angular would demand.
Eric Clemmons wrote a task for Grunt that applies the JSX transformation to your Javascript files. It also works with Browserify if you want all your files to be concatenated and minified together.
Grunt task for compiling Facebook React's .jsx templates into .js
Joel Burget wrote a blog post talking about the way we would write React-like components in Backbone and Handlebars.
The problem here is that we're trying to maniplate a tree, but there's a textual layer we have to go through. Our views are represented as a tree - the subviews are children of CommentCollectionView - and they end up as part of a tree in the DOM. But there's a Handlebars layer in the middle (which deals in flat strings), so the hierarchy must be destructed and rebuilt when we render.
What does it take to render a collection view? In the Backbone/Handlebars view of the world you have to render the template (with stubs), render each subview which replaces a stub, and keep a reference to each subview (or anything within the view that could change in the future).
So while our view is conceptually hierarchical, due to the fact that it has to go through a flat textual representation, we need to do a lot of extra work to reassemble that structure after rendering.
Vjeux used the fact that JSX is just a syntactic sugar on-top of regular JS to rewrite the React front-page examples in CoffeeScript.
Multiple people asked what's the story about JSX and CoffeeScript. There is no JSX pre-processor for CoffeeScript and I'm not aware of anyone working on it. Fortunately, CoffeeScript is pretty expressive and we can play around the syntax to come up with something that is usable.
We've seen a lot of people comparing React with various frameworks. Ricardo Tomasi decided to re-implement the tutorial without any framework, just plain Javascript.
Facebook & Instagram launched the React framework and an accompanying tutorial. Developer Vlad Yazhbin decided to rewrite that using AngularJS. The end result is pretty neat, but if you're like me you will not actually appreciate the HTML speaking for itself and doing all the hard work. So let's see what that looks like in plain javascript.
We have a ton of great stuff coming in v0.4, but in the meantime we're releasing v0.3.3. This release addresses some small issues people were having and simplifies our tools to make them easier to use.
Upgrade Commoner so require statements are no longer relativized when passing through the transformer. This was a feature needed when building React, but doesn't translate well for other consumers of bin/jsx.
Upgraded our dependencies on Commoner and Recast so they use a different directory for their cache.
Allow reusing the same DOM node to render different components. e.g. React.renderComponent(<div/>, domNode); React.renderComponent(<span/>, domNode); will work now.
Improved the in-browser transformer so that transformed scripts will execute in the expected scope. The allows components to be defined and used from separate files.
Andrew Greig made a blog post that gives a high level description of what React is.
I have been using Facebooks recently released Javascript framework called React.js for the last few days and have managed to obtain a rather high level understanding of how it works and formed a good perspective on how it fits in to the entire javascript framework ecosystem.
Basically, React is not an MVC framework. It is not a replacement for Backbone or Knockout or Angular, instead it is designed to work with existing frameworks and help extend their functionality.
It is designed for building big UIs. The type where you have lots of reusable components that are handling events and presenting and changing some backend data. In a traditional MVC app, React fulfils the role of the View. So you would still need to handle the Model and Controller on your own.
I found the best way to utilise React was to pair it with Backbone, with React replacing the Backbone View, or to write your own Model/Data object and have React communicate with that.
Danial Khosravi made a real-time chat application that interacts with the back-end using Socket.IO.
A week ago I was playing with AngularJS and this little chat application which uses socket.io and nodejs for realtime communication. Yesterday I saw a post about ReactJS in EchoJS and started playing with this UI library. After playing a bit with React, I decided to write and chat application using React and I used Bran Ford's Backend for server side of this little app.
Pete Hunt wrote an answer on Quora comparing React and Angular directives. At the end, he explains how you can make an Angular directive that is in fact being rendered with React.
To set the record straight: React components are far more powerful than Angular templates; they should be compared with Angular's directives instead. So I took the first Google hit for "AngularJS directive tutorial" (AngularJS Directives Tutorial - Fundoo Solutions), rewrote it in React and compared them. [...]
We've designed React from the beginning to work well with other libraries. Angular is no exception. Let's take the original Angular example and use React to implement the fundoo-rating directive.
Mozilla and Google are actively working on Web Components. Vjeux wrote a proof of concept that shows how to implement them using React.
Using x-tags from Mozilla, we can write custom tags within the DOM. This is a great opportunity to be able to write reusable components without being tied to a particular library. I wrote x-react to have them being rendered in React.
TodoMVC.com is a website that collects various implementations of the same basic Todo app. Pete Hunt wrote an idiomatic React version.
Developers these days are spoiled with choice when it comes to selecting an MV* framework for structuring and organizing their JavaScript web apps.
To help solve this problem, we created TodoMVC - a project which offers the same Todo application implemented using MV* concepts in most of the popular JavaScript MV* frameworks of today.
Many of you pointed out differences between JSX and HTML. In order to clear up some confusion, we have added some documentation that covers the four main differences:
React
