This will let us keep docs in order on the filesystem but have
reasonable permalinks. If we add something at 02- it doesn't result in
lots of broken links.
React is a JavaScript library for creating user interfaces by Facebook and Instagram. Many people choose to think of React as the **V** in **[MVC](http://en.wikipedia.org/wiki/Model%E2%80%93view%E2%80%93controller)**.
The most basic thing you can do with a UI is display some data. React makes it easy to display data, and automatically keeps it up-to-date when the data changes.
So far, we've looked at how to write a single component to display data and handle user input. Next let's examine one of React's finest features: composability.
When designing interfaces, break down the common design elements (buttons, form fields, layout components, etc) into reusable components with well-defined interfaces. That way, the next time you need to build some UI you can write much less code, which means faster development time, less bugs, and less bytes down the wire.
@ -40,7 +41,7 @@ React.renderComponent(
Components are the best way to reuse code in React, but sometimes very different components may share some common functionality. These are sometimes called [cross-cutting concerns](http://en.wikipedia.org/wiki/Cross-cutting_concern). React provides `mixins` to solve this problem.
One common use case is a component wanting to update itself on a time interval. It's easy to use `setInterval()`, but it's important to cancel your interval when you don't need it anymore to save memory. React provides [lifecycle methods](./06-working-with-the-browser.html) that let you know when a component is about to be created or destroyed. Let's create a simple mixin that uses these methods to provide an easy `setInterval()` function that will automatically get cleaned up when your component is destroyed.
One common use case is a component wanting to update itself on a time interval. It's easy to use `setInterval()`, but it's important to cancel your interval when you don't need it anymore to save memory. React provides [lifecycle methods](./working-with-the-browser.html) that let you know when a component is about to be created or destroyed. Let's create a simple mixin that uses these methods to provide an easy `setInterval()` function that will automatically get cleaned up when your component is destroyed.
Form components such as `<input>`, `<textarea>`, and `<option>` differ from other native components because they can be mutated via user interactions. These components provide interfaces that make it easier to manage forms in response to user interactions.
React provides powerful abstractions that free you from touching the DOM directly in most cases, but sometimes you simply need to access the underlying API, perhaps to work with a third-party library or existing code.
@ -55,7 +56,7 @@ React.renderComponent(
## More About Refs
To learn more about refs, including ways to use them effectively, see our [more about refs](./07.1-more-about-refs.html) documentation.
To learn more about refs, including ways to use them effectively, see our [more about refs](./more-about-refs.html) documentation.
After returning the structure of your UI from the render method, you may find yourself wanting to "reach out" and invoke methods on component instances returned from render. Often, doing something like this isn't necessary for making data flow through your application, because the Reactive data flow always ensures that the most recent `props` are sent to each child that is output from `render()`. However there are a few cases, where it still might be necessary or beneficial.
Paul O’Shannessy
12 years ago