There are a lot of JavaScript MVC frameworks out there. Why did we build React, and why would you want to use it?
First of all, **React is not an MVC framework**. It's a library designed for building big UIs. The type where you have lots of reusable components that are handling events, presenting backend data, and accepting user input. The type where you have to integrate with legacy code, and support legacy browsers.
## React is not an MVC framework.
It's a library designed for building big UIs. The type where you have lots of reusable components that are handling events, presenting backend data, and accepting user input. The type where you have to integrate with legacy code, and support legacy browsers.
In a conventional MVC application, you'd build the View with React (and maybe the Controller too, if you'd like).
## React doesn't use templates.
Traditionally, you'd create a set of templates with a template language or HTML directives to make a page dynamic. It's up to the designer of the template language or the author of the directives to provide the full set of abstractions you can use to build your front-end code.
React's technique is to break your view down into small, composable and reusable **components**. These components provide a `render()` method which specifies how the component will generate its markup. `render()` can either return normal DOM elements (like `<div>`s) or can return other components.
@ -18,10 +22,12 @@ This means that yes, we have JavaScript generating markup. But we think that thi
- **JavaScript is a flexible, powerful programming language with the ability to build abstractions.** This is incredibly important in large applications.
- "Logic" and "markup" are intimately tied, and are both part of the "presentation" layer, so we're not breaking separation of concerns.
- Large projects usually don't use WYSIWYG editors for production code
- Large projects usually don't use WYSIWYG editors for production code, so breaking apart markup from the code that creates it usually only introduces friction.
- We've built a safe, convenient and fast way to compose markup and components using pure JavaScript. This means no manual string concatenation and limited surface area for XSS vulnerabilities.
But the area where React really shines is when your data changes.
## Reacting to changes
React really shines when your data changes over time.
In a traditional JavaScript application you need to look at what data changed and imperatively make changes to the DOM to make them consistent. Even AngularJS, which provides a declarative interface via directives and data binding, still requires a linking function to manually update DOM nodes (remember: React components are quite flexible and analogous to AngularJS directives, not templates. In big apps you'll almost certainly need this level of expressive power).
@ -39,10 +45,12 @@ Because this re-render is so fast (on the order of 1ms for TodoMVC), we don't ne
No other framework we've seen can support this easily, since it would have to be built from the ground up to have very little coupling with the DOM.
## Not just for HTML components in the browser
Since React makes so few assumptions about its environment, we can do some pretty cool things with it:
- Facebook.com 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.
- Instagram is a "single page" web app built entirely with React and `Backbone.Router`. Designers regularly contribute React code with JSX.
- We've built an internal prototype that runs React apps in a web worker
- You can run React [on the server](http://github.com/petehunt/react-server-rendering) 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](http://davidwalsh.name/event-delegate)
petehunt
12 years ago