# styled-jsx

Full, scoped and component-friendly CSS support for JSX (SSR+browser)

## How it works

Just include `<style jsx>`.

```js
export default () => (
  <div>
    <p>only this paragraph will get the style :O</p>
    { /* you can include <Component />s here that include
         other <p>s that don't get unexpected styles! */ }
    <style jsx>{`
      p {
        color: red;
      }
    `}</style>
  </div>
)
```

## Features

- Full CSS support, no tradeoffs in power
- Runtime size: *300b*
- Complete isolation: selectors, animations, keyframes
- Built in CSS prefixing
- Very fast, minimal and efficient transpilation (see below)
- High performant runtime CSS injection when not server-rendering
- Future-proof: equivalent to server-renderable "Shadow CSS"
- Works like the deprecated `<style scoped>`, but the styles
  get injected only once per component

## How it works

The example above compiles to

```js
import _jsxStyleInject from 'styled-jsx/inject'
export default () => (
  <div>
    <p data-jsx='cn2o3j'>only this paragraph will get the style :O</p>
    { _jsxStyleInject('cn2o3j', `p[data-jsx=cn2o3j] {color: red;}`) }
  </div>
)
```

- Data attributes give us style encapsulation.
- `_jsxStyleInject` is heavily optimized for:
	- injecting styles upon render
	- only injecting a certain componen'ts style once, even if the component is included multiple times
	- keeping track of styles for server-side rendering

## How to use

Add `styled-jsx` to `dependencies` inside `package.json`

### Babel

Add `styled-jsx/babel` to `plugins` in your babel configuration

### Server-side rendering

In the server rendering pipeline, you can obtain the entire
CSS text of all the combined components by invoking `flush`

```js
import flush from 'styled-jsx/flush'
// …
// <render here>
// …
const styles = flush()
for (let id in styles) {
  const css = styles[id]
  console.log(id, css)
}
```

This API is also available on the client. Instead of returning
the CSS text, it returns a reference to the created `<style>` tag.

This is useful for performing diffs of elements between top-level
`render()` calls, and ditching style elements that are not longer
used.

## Credits

- Pedram Emrouznejad ([`rijs`](https://github.com/rijs/fullstack))
  - suggesting attribute selectors over my initial class prefixing idea
- Sunil Pail ([`glamor`](https://github.com/threepointone/glamor))
  - inspired usage of `murmurhash2` (minimal and fast hashing)
  - efficient style injection logic
- Sultan Tarimo ([`stylis.js`](https://github.com/thysultan))
  - super fast and tiny CSS parser and compiler
- Max Stoiber ([`styled-components`](https://github.com/styled-components))
  - proved the value of retaining the familiarity of CSS syntax
  - pointed me to the very efficient [`stylis`](https://github.com/thysultan/stylis.js)
    compiler which we forked to very efficiently append attribute selectors
    to the user's css
- Yehuda Katz ([`ember`](https://github.com/ember))
  - convinced me on Twitter to transpile CSS as an alternative to CSS-in-JS
- Evan You ([`vuejs`](https://github.com/vuejs))
  - discussing his Vue.js CSS transformation
- Henry Zhu ([`babel`](https://github.com/babel))
  - his helpful pointers on the babel plugin API

## Author

Guillermo Rauch ([@rauchg](https://twitter.com/rauchg) - [▲ZEIT](https://zeit.co)