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| .github | ||
| bench | ||
| bin | ||
| client | ||
| errors | ||
| examples | ||
| lib | ||
| pages | ||
| server | ||
| test | ||
| .babelrc | ||
| .gitignore | ||
| .npmrc | ||
| .travis.yml | ||
| appveyor.yml | ||
| babel.js | ||
| client.js | ||
| contributing.md | ||
| css.js | ||
| document.js | ||
| dynamic.js | ||
| error.js | ||
| head.js | ||
| license.md | ||
| link.js | ||
| package.json | ||
| prefetch.js | ||
| readme.md | ||
| router.js | ||
| taskfile.js | ||
| wallaby.js | ||
| yarn.lock | ||
Next.js is a minimalistic framework for server-rendered React applications.
Visit learnnextjs.com to get started with Next.js.
- How to use
- Setup
- Automatic code splitting
- CSS
- Static file serving (e.g.: images)
- Populating
<head> - Fetching data and component lifecycle
- Routing
- Prefetching Pages
- Custom server and routing
- Dynamic Import
- Custom
<Document> - Custom error handling
- Custom configuration
- Customizing webpack config
- Customizing babel config
- CDN support with Asset Prefix
- Production deployment
- Static HTML export
- Recipes
- FAQ
- Contributing
- Authors
How to use
Setup
Install it:
npm install --save next react react-dom
Next.js 4 only supports React 16.
We had to drop React 15 support due to the way React 16 works and how we use it.
and add a script to your package.json like this:
{
"scripts": {
"dev": "next",
"build": "next build",
"start": "next start"
}
}
After that, the file-system is the main API. Every .js file becomes a route that gets automatically processed and rendered.
Populate ./pages/index.js inside your project:
export default () => <div>Welcome to next.js!</div>
and then just run npm run dev and go to http://localhost:3000. To use another port, you can run npm run dev -- -p <your port here>.
So far, we get:
- Automatic transpilation and bundling (with webpack and babel)
- Hot code reloading
- Server rendering and indexing of
./pages - Static file serving.
./static/is mapped to/static/
To see how simple this is, check out the sample app - nextgram
Automatic code splitting
Every import you declare gets bundled and served with each page. That means pages never load unnecessary code!
import cowsay from 'cowsay-browser'
export default () =>
<pre>
{cowsay.say({ text: 'hi there!' })}
</pre>
CSS
Built-in CSS support
Examples
We bundle styled-jsx to provide support for isolated scoped CSS. The aim is to support "shadow CSS" similar to Web Components, which unfortunately do not support server-rendering and are JS-only.
export default () =>
<div>
Hello world
<p>scoped!</p>
<style jsx>{`
p {
color: blue;
}
div {
background: red;
}
@media (max-width: 600px) {
div {
background: blue;
}
}
`}</style>
<style global jsx>{`
body {
background: black;
}
`}</style>
</div>
Please see the styled-jsx documentation for more examples.
CSS-in-JS
It's possible to use any existing CSS-in-JS solution. The simplest one is inline styles:
export default () => <p style={{ color: 'red' }}>hi there</p>
To use more sophisticated CSS-in-JS solutions, you typically have to implement style flushing for server-side rendering. We enable this by allowing you to define your own custom <Document> component that wraps each page.
Static file serving (e.g.: images)
Create a folder called static in your project root directory. From your code you can then reference those files with /static/ URLs:
export default () => <img src="/static/my-image.png" />
Populating <head>
Examples
We expose a built-in component for appending elements to the <head> of the page.
import Head from 'next/head'
export default () =>
<div>
<Head>
<title>My page title</title>
<meta name="viewport" content="initial-scale=1.0, width=device-width" />
</Head>
<p>Hello world!</p>
</div>
To avoid duplicate tags in your <head> you can use the key property, which will make sure the tag is only rendered once:
import Head from 'next/head'
export default () => (
<div>
<Head>
<title>My page title</title>
<meta name="viewport" content="initial-scale=1.0, width=device-width" key="viewport" />
</Head>
<Head>
<meta name="viewport" content="initial-scale=1.2, width=device-width" key="viewport" />
</Head>
<p>Hello world!</p>
</div>
)
In this case only the second <meta name="viewport" /> is rendered.
Note: The contents of <head> get cleared upon unmounting the component, so make sure each page completely defines what it needs in <head>, without making assumptions about what other pages added
Fetching data and component lifecycle
Examples
When you need state, lifecycle hooks or initial data population you can export a React.Component (instead of a stateless function, like shown above):
import React from 'react'
export default class extends React.Component {
static async getInitialProps({ req }) {
const userAgent = req ? req.headers['user-agent'] : navigator.userAgent
return { userAgent }
}
render() {
return (
<div>
Hello World {this.props.userAgent}
</div>
)
}
}
Notice that to load data when the page loads, we use getInitialProps which is an async static method. It can asynchronously fetch anything that resolves to a JavaScript plain Object, which populates props.
For the initial page load, getInitialProps will execute on the server only. getInitialProps will only be executed on the client when navigating to a different route via the Link component or using the routing APIs.
Note: getInitialProps can not be used in children components. Only in pages.
If you are using some server only modules inside
getInitialProps, make sure to import them properly. Otherwise, it'll slow down your app.
You can also define the getInitialProps lifecycle method for stateless components:
const Page = ({ stars }) =>
<div>
Next stars: {stars}
</div>
Page.getInitialProps = async ({ req }) => {
const res = await fetch('https://api.github.com/repos/zeit/next.js')
const json = await res.json()
return { stars: json.stargazers_count }
}
export default Page
getInitialProps receives a context object with the following properties:
pathname- path section of URLquery- query string section of URL parsed as an objectasPath-Stringof the actual path (including the query) shows in the browserreq- HTTP request object (server only)res- HTTP response object (server only)jsonPageRes- Fetch Response object (client only)err- Error object if any error is encountered during the rendering
Routing
With <Link>
Examples
Client-side transitions between routes can be enabled via a <Link> component. Consider these two pages:
// pages/index.js
import Link from 'next/link'
export default () =>
<div>
Click{' '}
<Link href="/about">
<a>here</a>
</Link>{' '}
to read more
</div>
// pages/about.js
export default () => <p>Welcome to About!</p>
Note: use <Link prefetch> for maximum performance, to link and prefetch in the background at the same time
Client-side routing behaves exactly like the browser:
- The component is fetched
- If it defines
getInitialProps, data is fetched. If an error occurs,_error.jsis rendered - After 1 and 2 complete,
pushStateis performed and the new component is rendered
Each top-level component receives a url property with the following API:
pathname-Stringof the current path excluding the query stringquery-Objectwith the parsed query string. Defaults to{}asPath-Stringof the actual path (including the query) shows in the browserpush(url, as=url)- performs apushStatecall with the given urlreplace(url, as=url)- performs areplaceStatecall with the given url
The second as parameter for push and replace is an optional decoration of the URL. Useful if you configured custom routes on the server.
With URL object
Examples
The component <Link> can also receive an URL object and it will automatically format it to create the URL string.
// pages/index.js
import Link from 'next/link'
export default () =>
<div>
Click{' '}
<Link href={{ pathname: '/about', query: { name: 'Zeit' } }}>
<a>here</a>
</Link>{' '}
to read more
</div>
That will generate the URL string /about?name=Zeit, you can use every property as defined in the Node.js URL module documentation.
Replace instead of push url
The default behaviour for the <Link> component is to push a new url into the stack. You can use the replace prop to prevent adding a new entry.
// pages/index.js
import Link from 'next/link'
export default () =>
<div>
Click{' '}
<Link href="/about" replace>
<a>here</a>
</Link>{' '}
to read more
</div>
Using a component that supports onClick
<Link> supports any component that supports the onClick event. In case you don't provide an <a> tag, it will only add the onClick event handler and won't pass the href property.
// pages/index.js
import Link from 'next/link'
export default () =>
<div>
Click{' '}
<Link href="/about">
<img src="/static/image.png" />
</Link>
</div>
Forcing the Link to expose href to its child
If child is an <a> tag and doesn't have a href attribute we specify it so that the repetition is not needed by the user. However, sometimes, you’ll want to pass an <a> tag inside of a wrapper and the Link won’t recognize it as a hyperlink, and, consequently, won’t transfer its href to the child. In cases like that, you should define a boolean passHref property to the Link, forcing it to expose its href property to the child.
Please note: using a tag other than a and failing to pass passHref may result in links that appear to navigate correctly, but, when being crawled by search engines, will not be recognized as links (owing to the lack of href attribute). This may result in negative effects on your sites SEO.
import Link from 'next/link'
import Unexpected_A from 'third-library'
export default ({ href, name }) =>
<Link href={href} passHref>
<Unexpected_A>
{name}
</Unexpected_A>
</Link>
Imperatively
You can also do client-side page transitions using the next/router
import Router from 'next/router'
export default () =>
<div>
Click <span onClick={() => Router.push('/about')}>here</span> to read more
</div>
Above Router object comes with the following API:
route-Stringof the current routepathname-Stringof the current path excluding the query stringquery-Objectwith the parsed query string. Defaults to{}asPath-Stringof the actual path (including the query) shows in the browserpush(url, as=url)- performs apushStatecall with the given urlreplace(url, as=url)- performs areplaceStatecall with the given url
The second as parameter for push and replace is an optional decoration of the URL. Useful if you configured custom routes on the server.
Note: in order to programmatically change the route without triggering navigation and component-fetching, use props.url.push and props.url.replace within a component
With URL object
You can use an URL object the same way you use it in a <Link> component to push and replace an url.
import Router from 'next/router'
const handler = () =>
Router.push({
pathname: '/about',
query: { name: 'Zeit' }
})
export default () =>
<div>
Click <span onClick={handler}>here</span> to read more
</div>
This uses of the same exact parameters as in the <Link> component.
Router Events
You can also listen to different events happening inside the Router. Here's a list of supported events:
onRouteChangeStart(url)- Fires when a route starts to changeonRouteChangeComplete(url)- Fires when a route changed completelyonRouteChangeError(err, url)- Fires when there's an error when changing routesonBeforeHistoryChange(url)- Fires just before changing the browser's historyonAppUpdated(nextRoute)- Fires when switching pages and there's a new version of the app
Here
urlis the URL shown in the browser. If you callRouter.push(url, as)(or similar), then the value ofurlwill beas.
Here's how to properly listen to the router event onRouteChangeStart:
Router.onRouteChangeStart = url => {
console.log('App is changing to: ', url)
}
If you no longer want to listen to that event, you can simply unset the event listener like this:
Router.onRouteChangeStart = null
If a route load is cancelled (for example by clicking two links rapidly in succession), routeChangeError will fire. The passed err will contain a cancelled property set to true.
Router.onRouteChangeError = (err, url) => {
if (err.cancelled) {
console.log(`Route to ${url} was cancelled!`)
}
}
If you change a route while in between a new deployment, we can't navigate the app via client side. We need to do a full browser navigation. We do it automatically for you.
But you can customize that via Route.onAppUpdated event like this:
Router.onAppUpdated = nextUrl => {
// persist the local state
location.href = nextUrl
}
Shallow Routing
Examples
Shallow routing allows you to change the URL without running getInitialProps. You'll receive the updated pathname and the query via the url prop of the same page that's loaded, without losing state.
You can do this by invoking either Router.push or Router.replace with the shallow: true option. Here's an example:
// Current URL is "/"
const href = '/?counter=10'
const as = href
Router.push(href, as, { shallow: true })
Now, the URL is updated to /?counter=10. You can see the updated URL with this.props.url inside the Component.
You can watch for URL changes via componentWillReceiveProps hook as shown below:
componentWillReceiveProps(nextProps) {
const { pathname, query } = nextProps.url
// fetch data based on the new query
}
NOTES:
Shallow routing works only for same page URL changes. For an example, let's assume we've another page called
about, and you run this:Router.push('/about?counter=10', '/about?counter=10', { shallow: true })Since that's a new page, it'll unload the current page, load the new one and call
getInitialPropseven though we asked to do shallow routing.
Using a Higher Order Component
Examples
If you want to access the router object inside any component in your app, you can use the withRouter Higher-Order Component. Here's how to use it:
import { withRouter } from 'next/router'
const ActiveLink = ({ children, router, href }) => {
const style = {
marginRight: 10,
color: router.pathname === href? 'red' : 'black'
}
const handleClick = (e) => {
e.preventDefault()
router.push(href)
}
return (
<a href={href} onClick={handleClick} style={style}>
{children}
</a>
)
}
export default withRouter(ActiveLink)
The above router object comes with an API similar to next/router.
Prefetching Pages
(This is a production only feature)
Examples
Next.js has an API which allows you to prefetch pages.
Since Next.js server-renders your pages, this allows all the future interaction paths of your app to be instant. Effectively Next.js gives you the great initial download performance of a website, with the ahead-of-time download capabilities of an app. Read more.
With prefetching Next.js only downloads JS code. When the page is getting rendered, you may need to wait for the data.
With <Link>
You can add prefetch prop to any <Link> and Next.js will prefetch those pages in the background.
import Link from 'next/link'
// example header component
export default () =>
<nav>
<ul>
<li>
<Link prefetch href="/">
<a>Home</a>
</Link>
</li>
<li>
<Link prefetch href="/about">
<a>About</a>
</Link>
</li>
<li>
<Link prefetch href="/contact">
<a>Contact</a>
</Link>
</li>
</ul>
</nav>
Imperatively
Most prefetching needs are addressed by <Link />, but we also expose an imperative API for advanced usage:
import Router from 'next/router'
export default ({ url }) =>
<div>
<a onClick={() => setTimeout(() => url.pushTo('/dynamic'), 100)}>
A route transition will happen after 100ms
</a>
{// but we can prefetch it!
Router.prefetch('/dynamic')}
</div>
Custom server and routing
Examples
Typically you start your next server with next start. It's possible, however, to start a server 100% programmatically in order to customize routes, use route patterns, etc.
When using a custom server with a server file, for example called server.js, make sure you update the scripts key in package.json to:
{
"scripts": {
"dev": "node server.js",
"build": "next build",
"start": "NODE_ENV=production node server.js"
}
}
This example makes /a resolve to ./pages/b, and /b resolve to ./pages/a:
// This file doesn't not go through babel or webpack transformation.
// Make sure the syntax and sources this file requires are compatible with the current node version you are running
// See https://github.com/zeit/next.js/issues/1245 for discussions on Universal Webpack or universal Babel
const { createServer } = require('http')
const { parse } = require('url')
const next = require('next')
const dev = process.env.NODE_ENV !== 'production'
const app = next({ dev })
const handle = app.getRequestHandler()
app.prepare().then(() => {
createServer((req, res) => {
// Be sure to pass `true` as the second argument to `url.parse`.
// This tells it to parse the query portion of the URL.
const parsedUrl = parse(req.url, true)
const { pathname, query } = parsedUrl
if (pathname === '/a') {
app.render(req, res, '/b', query)
} else if (pathname === '/b') {
app.render(req, res, '/a', query)
} else {
handle(req, res, parsedUrl)
}
}).listen(3000, err => {
if (err) throw err
console.log('> Ready on http://localhost:3000')
})
})
The next API is as follows:
next(opts: object)
Supported options:
dev(bool) whether to launch Next.js in dev mode - defaultfalsedir(string) where the Next project is located - default'.'quiet(bool) Hide error messages containing server information - defaultfalseconf(object) the same object you would use innext.config.js- default{}
Then, change your start script to NODE_ENV=production node server.js.
Disabling file-system routing
By default, Next will serve each file in /pages under a pathname matching the filename (eg, /pages/some-file.js is served at site.com/some-file.
If your project uses custom routing, this behavior may result in the same content being served from multiple paths, which can present problems with SEO and UX.
To disable this behavior & prevent routing based on files in /pages, simply set the following option in your next.config.js:
// next.config.js
module.exports = {
useFileSystemPublicRoutes: false
}
Dynamic Import
Examples
Next.js supports TC39 dynamic import proposal for JavaScript. With that, you could import JavaScript modules (inc. React Components) dynamically and work with them.
You can think dynamic imports as another way to split your code into manageable chunks. Since Next.js supports dynamic imports with SSR, you could do amazing things with it.
Here are a few ways to use dynamic imports.
1. Basic Usage (Also does SSR)
import dynamic from 'next/dynamic'
const DynamicComponent = dynamic(import('../components/hello'))
export default () =>
<div>
<Header />
<DynamicComponent />
<p>HOME PAGE is here!</p>
</div>
2. With Custom Loading Component
import dynamic from 'next/dynamic'
const DynamicComponentWithCustomLoading = dynamic(
import('../components/hello2'),
{
loading: () => <p>...</p>
}
)
export default () =>
<div>
<Header />
<DynamicComponentWithCustomLoading />
<p>HOME PAGE is here!</p>
</div>
3. With No SSR
import dynamic from 'next/dynamic'
const DynamicComponentWithNoSSR = dynamic(import('../components/hello3'), {
ssr: false
})
export default () =>
<div>
<Header />
<DynamicComponentWithNoSSR />
<p>HOME PAGE is here!</p>
</div>
4. With Multiple Modules At Once
import dynamic from 'next/dynamic'
const HelloBundle = dynamic({
modules: props => {
const components = {
Hello1: import('../components/hello1'),
Hello2: import('../components/hello2')
}
// Add remove components based on props
return components
},
render: (props, { Hello1, Hello2 }) =>
<div>
<h1>
{props.title}
</h1>
<Hello1 />
<Hello2 />
</div>
})
export default () => <HelloBundle title="Dynamic Bundle" />
Custom <Document>
Pages in Next.js skip the definition of the surrounding document's markup. For example, you never include <html>, <body>, etc. To override that default behavior, you must create a file at ./pages/_document.js, where you can extend the Document class:
// ./pages/_document.js
import Document, { Head, Main, NextScript } from 'next/document'
import flush from 'styled-jsx/server'
export default class MyDocument extends Document {
static getInitialProps({ renderPage }) {
const { html, head, errorHtml, chunks } = renderPage()
const styles = flush()
return { html, head, errorHtml, chunks, styles }
}
render() {
return (
<html>
<Head>
<style>{`body { margin: 0 } /* custom! */`}</style>
</Head>
<body className="custom_class">
{this.props.customValue}
<Main />
<NextScript />
</body>
</html>
)
}
}
The ctx object is equivalent to the one received in all getInitialProps hooks, with one addition:
renderPage(Function) a callback that executes the actual React rendering logic (synchronously). It's useful to decorate this function in order to support server-rendering wrappers like Aphrodite'srenderStatic
Note: React-components outside of <Main /> will not be initialised by the browser. If you need shared components in all your pages (like a menu or a toolbar), do not add application logic here, but take a look at this example.
Custom error handling
404 or 500 errors are handled both client and server side by a default component error.js. If you wish to override it, define a _error.js in the pages folder:
import React from 'react'
export default class Error extends React.Component {
static getInitialProps({ res, err }) {
const statusCode = res ? res.statusCode : err ? err.statusCode : null;
return { statusCode }
}
render() {
return (
<p>
{this.props.statusCode
? `An error ${this.props.statusCode} occurred on server`
: 'An error occurred on client'}
</p>
)
}
}
Reusing the built-in error page
If you want to render the built-in error page you can by using next/error:
import React from 'react'
import Error from 'next/error'
import fetch from 'isomorphic-unfetch'
export default class Page extends React.Component {
static async getInitialProps() {
const res = await fetch('https://api.github.com/repos/zeit/next.js')
const statusCode = res.statusCode > 200 ? res.statusCode : false
const json = await res.json()
return { statusCode, stars: json.stargazers_count }
}
render() {
if (this.props.statusCode) {
return <Error statusCode={this.props.statusCode} />
}
return (
<div>
Next stars: {this.props.stars}
</div>
)
}
}
If you have created a custom error page you have to import your own
_errorcomponent instead ofnext/error
Custom configuration
For custom advanced behavior of Next.js, you can create a next.config.js in the root of your project directory (next to pages/ and package.json).
Note: next.config.js is a regular Node.js module, not a JSON file. It gets used by the Next server and build phases, and not included in the browser build.
// next.config.js
module.exports = {
/* config options here */
}
Setting a custom build directory
You can specify a name to use for a custom build directory. For example, the following config will create a build folder instead of a .next folder. If no configuration is specified then next will create a .next folder.
// next.config.js
module.exports = {
distDir: 'build'
}
Configuring the onDemandEntries
Next exposes some options that give you some control over how the server will dispose or keep in memories pages built:
module.exports = {
onDemandEntries: {
// period (in ms) where the server will keep pages in the buffer
maxInactiveAge: 25 * 1000,
// number of pages that should be kept simultaneously without being disposed
pagesBufferLength: 2,
}
}
This is development-only feature. If you want to cache SSR pages in production, please see SSR-caching example.
Customizing webpack config
Examples
In order to extend our usage of webpack, you can define a function that extends its config via next.config.js.
// This file is not going through babel transformation.
// So, we write it in vanilla JS
// (But you could use ES2015 features supported by your Node.js version)
module.exports = {
webpack: (config, { buildId, dev }) => {
// Perform customizations to webpack config
// Important: return the modified config
return config
},
webpackDevMiddleware: config => {
// Perform customizations to webpack dev middleware config
// Important: return the modified config
return config
}
}
Warning: Adding loaders to support new file types (css, less, svg, etc.) is not recommended because only the client code gets bundled via webpack and thus it won't work on the initial server rendering. Babel plugins are a good alternative because they're applied consistently between server/client rendering (e.g. babel-plugin-inline-react-svg).
Customizing babel config
Examples
In order to extend our usage of babel, you can simply define a .babelrc file at the root of your app. This file is optional.
If found, we're going to consider it the source of truth, therefore it needs to define what next needs as well, which is the next/babel preset.
This is designed so that you are not surprised by modifications we could make to the babel configurations.
Here's an example .babelrc file:
{
"presets": ["next/babel", "env"]
}
CDN support with Asset Prefix
To set up a CDN, you can set up the assetPrefix setting and configure your CDN's origin to resolve to the domain that Next.js is hosted on.
const isProd = process.env.NODE_ENV === 'production'
module.exports = {
// You may only need to add assetPrefix in the production.
assetPrefix: isProd ? 'https://cdn.mydomain.com' : ''
}
Note: Next.js will automatically use that prefix in the scripts it loads, but this has no effect whatsoever on /static. If you want to serve those assets over the CDN, you'll have to introduce the prefix yourself. One way of introducing a prefix that works inside your components and varies by environment is documented in this example.
Production deployment
To deploy, instead of running next, you want to build for production usage ahead of time. Therefore, building and starting are separate commands:
next build
next start
For example, to deploy with now a package.json like follows is recommended:
{
"name": "my-app",
"dependencies": {
"next": "latest"
},
"scripts": {
"dev": "next",
"build": "next build",
"start": "next start"
}
}
Then run now and enjoy!
Next.js can be deployed to other hosting solutions too. Please have a look at the 'Deployment' section of the wiki.
Note: NODE_ENV is properly configured by the next subcommands, if absent, to maximize performance. if you’re using Next.js programmatically, it’s your responsibility to set NODE_ENV=production manually!
Note: we recommend putting .next, or your custom dist folder (Please have a look at 'Custom Config'. You can set a custom folder in config, .npmignore, or .gitignore. Otherwise, use files or now.files to opt-into a whitelist of files you want to deploy (and obviously exclude .next or your custom dist folder).
Static HTML export
Examples
This is a way to run your Next.js app as a standalone static app without any Node.js server. The export app supports almost every feature of Next.js including dynamic urls, prefetching, preloading and dynamic imports.
Usage
Simply develop your app as you normally do with Next.js. Then create a custom Next.js config as shown below:
// next.config.js
module.exports = {
exportPathMap: function() {
return {
'/': { page: '/' },
'/about': { page: '/about' },
'/readme.md': { page: '/readme' },
'/p/hello-nextjs': { page: '/post', query: { title: 'hello-nextjs' } },
'/p/learn-nextjs': { page: '/post', query: { title: 'learn-nextjs' } },
'/p/deploy-nextjs': { page: '/post', query: { title: 'deploy-nextjs' } }
}
}
}
Note that if the path ends with a directory, it will be exported as
/dir-name/index.html, but if it ends with an extension, it will be exported as the specified filename, e.g./readme.mdabove. If you use a file extension other than.html, you may need to set theContent-Typeheader totext/htmlwhen serving this content.
In that, you specify what are the pages you need to export as static HTML.
Then simply run these commands:
next build
next export
For that you may need to add a NPM script to package.json like this:
{
"scripts": {
"build": "next build && next export"
}
}
And run it at once with:
npm run build
Then you've a static version of your app in the “out" directory.
You can also customize the output directory. For that run
next export -hfor the help.
Now you can deploy that directory to any static hosting service. Note that there is an additional step for deploying to GitHub Pages, documented here.
For an example, simply visit the “out” directory and run following command to deploy your app to ZEIT now.
now
Limitation
With next export, we build HTML version of your app when you run the command next export. In that time, we'll run the getInitialProps functions of your pages.
So, you could only use pathname, query and asPath fields of the context object passed to getInitialProps. You can't use req or res fields.
Basically, you won't be able to render HTML content dynamically as we pre-build HTML files. If you need that, you need run your app with
next start.
Recipes
FAQ
Is this production ready?
Next.js has been powering https://zeit.co since its inception.We’re ecstatic about both the developer experience and end-user performance, so we decided to share it with the community.
How big is it?
The client side bundle size should be measured in a per-app basis. A small Next main bundle is around 65kb gzipped.
Is this like `create-react-app`?
Yes and No.
Yes in that both make your life easier.
No in that it enforces a structure so that we can do more advanced things like:
- Server side rendering
- Automatic code splitting
In addition, Next.js provides two built-in features that are critical for every single website:
- Routing with lazy component loading:
<Link>(by importingnext/link) - A way for components to alter
<head>:<Head>(by importingnext/head)
If you want to create re-usable React components that you can embed in your Next.js app or other React applications, using create-react-app is a great idea. You can later import it and keep your codebase clean!
How do I use CSS-in-JS solutions?
Next.js bundles styled-jsx supporting scoped css. However you can use any CSS-in-JS solution in your Next app by just including your favorite library as mentioned before in the document.
How do I use CSS preprocessors like SASS / SCSS / LESS?
Next.js bundles styled-jsx supporting scoped css. However you can use any CSS preprocessor solution in your Next app by following one of these examples:
What syntactic features are transpiled? How do I change them?
We track V8. Since V8 has wide support for ES6 and async and await, we transpile those. Since V8 doesn’t support class decorators, we don’t transpile those.
Why a new Router?
Next.js is special in that:
- Routes don’t need to be known ahead of time
- Routes are always lazy-loadable
- Top-level components can define
getInitialPropsthat should block the loading of the route (either when server-rendering or lazy-loading)
As a result, we were able to introduce a very simple approach to routing that consists of two pieces:
- Every top level component receives a
urlobject to inspect the url or perform modifications to the history - A
<Link />component is used to wrap elements like anchors (<a/>) to perform client-side transitions
We tested the flexibility of the routing with some interesting scenarios. For an example, check out nextgram.
How do I define a custom fancy route?
We added the ability to map between an arbitrary URL and any component by supplying a request handler.
On the client side, we have a parameter call as on <Link> that decorates the URL differently from the URL it fetches.
How do I fetch data?
It’s up to you. getInitialProps is an async function (or a regular function that returns a Promise). It can retrieve data from anywhere.
Can I use it with GraphQL?
Yes! Here's an example with Apollo.
Can I use it with Redux?
Yes! Here's an example
Why aren't routes I have for my static export accessible in the development server?
This is a known issue with the architecture of Next.js. Until a solution is built into the framework, take a look at this example solution to centralize your routing.
Can I use Next with my favorite Javascript library or toolkit?
Since our first release we've had many example contributions, you can check them out in the examples directory
What is this inspired by?
Many of the goals we set out to accomplish were the ones listed in The 7 principles of Rich Web Applications by Guillermo Rauch.
The ease-of-use of PHP is a great inspiration. We feel Next.js is a suitable replacement for many scenarios where you otherwise would use PHP to output HTML.
Unlike PHP, we benefit from the ES6 module system and every file exports a component or function that can be easily imported for lazy evaluation or testing.
As we were researching options for server-rendering React that didn’t involve a large number of steps, we came across react-page (now deprecated), a similar approach to Next.js by the creator of React Jordan Walke.
Contributing
Please see our contributing.md
Authors
- Arunoda Susiripala (@arunoda) – ▲ZEIT
- Tim Neutkens (@timneutkens)
- Naoyuki Kanezawa (@nkzawa) – ▲ZEIT
- Tony Kovanen (@tonykovanen) – ▲ZEIT
- Guillermo Rauch (@rauchg) – ▲ZEIT
- Dan Zajdband (@impronunciable) – Knight-Mozilla / Coral Project