React is a library for building composable user interfaces. It encourages the creation of reusable UI components which present data that changes over time.
Traditionally, web application UIs are built using templates or HTML directives. These templates dictate the full set of abstractions that you are allowed to use to build your UI.
React approaches building user interfaces differently by breaking them into components. This means React uses a real, full featured programming language to render views, which we see as an advantage over templates for a few reasons:
- By unifying your markup with its corresponding view logic, React can actually make views easier to extend and maintain.
React really shines when your data changes over time.
React takes a different approach.
When your component is first initialized, the
render method is called,
generating a lightweight representation of your view. From that representation,
a string of markup is produced, and injected into the document. When your data
render method is called again. In order to perform updates as
efficiently as possible, we diff the return value from the previous call to
render with the new one, and generate a minimal set of changes to be applied
to the DOM.
The data returned from
renderis neither a string nor a DOM node — it’s a lightweight description of what the DOM should look like.
We call this process reconciliation. Check out this jsFiddle to see an example of reconciliation in action.
Because this re-render is so fast (around 1ms for TodoMVC), the developer doesn’t need to explicitly specify data bindings. We’ve found this approach makes it easier to build apps.
Because React has its own lightweight representation of the document, we can do some pretty cool things with it:
- Facebook has dynamic charts that render to
<canvas>instead of HTML.
- Instagram is a “single page” web app built entirely with React and
Backbone.Router. Designers regularly contribute React code with JSX.
- We’ve built internal prototypes that run React apps in a web worker and use React to drive native iOS views via an Objective-C bridge.
- You can run React on the server for SEO, performance, code sharing and overall flexibility.
- Events behave in a consistent, standards-compliant way in all browsers (including IE8) and automatically use event delegation.
Head on over to https://reactjs.org to check out what we have built. Our documentation is geared towards building apps with the framework, but if you are interested in the nuts and bolts get in touch with us!
Thanks for reading!