next js上线（Next.js入门使用教程）

mkdir nextDemo  //创建项目
npm init            //初始化项目
npm i react react-dom next --save           //添加依赖

 "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "dev" : "next" ,
    "build" : " next build",
    "start" : "next start"
  },

function Index(){
    return (
        <li>Hello Next.js</li>
    )
}
export default Index

npm run dev

npm install -g create-next-app  //全局安装脚手架
create-next-app nextDemo  //基于脚手架创建项目
cd nextDemo
npm run dev  //运行项目

import React from 'react'
import Link from 'next/link'
const Home = () => (
  <>
    <li>我是首页</li>
    <li><Link href="/pageA" rel="external nofollow"  rel="external nofollow"  rel="external nofollow" ><a>去A页面</a></Link></li>
    <li><Link href="/pageB" rel="external nofollow" ><a>去B页面</a></Link></li>

  </>
)

export default Home

 //错误写法
 <li>
  <Link href="/pageA" rel="external nofollow"  rel="external nofollow"  rel="external nofollow" >
    <span>去A页面</span>
    <span>前端博客</span>
  </Link>
</li>

//正确写法
<Link href="/pageA" rel="external nofollow"  rel="external nofollow"  rel="external nofollow" >
  <a>
    <span>去A页面</span>
    <span>前端博客</span>
  </a>
</Link>

import Router from 'next/router'

<button onClick={()=>{Router.push('/pageA')}}>去A页面</button>

import Link from 'next/link'

//传递
<Link href="/blogDetail?bid=23" rel="external nofollow" ><a>{blog.title}</a></Link>

    
    
//blog.js
import { withRouter} from 'next/router'
import Link from 'next/link'

const BlogDetail = ({router})=>{
    return (
        <>
            <li>blog id: {router.query.name}</li>
            <Link href="/" rel="external nofollow" ><a>返回首页</a></Link>
        </>
    )
}
//withRouter是Next.js框架的高级组件，用来处理路由用的
export default withRouter(BlogDetail)


/************************************************************************************/
import Router from 'next/router'

<button onClick={gotoBlogDetail} >博客详情</button>

function gotoBlogDetail(){
    Router.push('/blogDetail?bid=23')
}

//object 形式
function gotoBlogDetail(){
    Router.push({
        pathname:"/blogDetail",
        query:{
            bid:23
        }
    })
}

<Link href={{pathname:'/blogDetail',query:{bid:23}}><a>博客详情</a></Link>

pages/post/[pid].js
route : /post/abc  -->  query : { "pid": "abc" }


pages/post/[pid]/[comment].js
route : /post/abc/a-comment  -->  query : { "pid": "abc", "comment": "a-comment" }

//路由发生变化时
Router.events.on('routeChangeStart',(...args)=>{
    console.log('1.routeChangeStart->路由开始变化,参数为:',...args)
})

//路由结束变化时
Router.events.on('routeChangeComplete',(...args)=>{
    console.log('routeChangeComplete->路由结束变化,参数为:',...args)
})

//浏览器 history触发前
Router.events.on('beforeHistoryChange',(...args)=>{
    console.log('3,beforeHistoryChange->在改变浏览器 history之前触发,参数为:',...args)
})

//路由跳转发生错误时
Router.events.on('routeChangeError',(...args)=>{
    console.log('4,routeChangeError->跳转发生错误,参数为:',...args)
})

/****************************hash路由***********************************/

Router.events.on('hashChangeStart',(...args)=>{
    console.log('5,hashChangeStart->hash跳转开始时执行,参数为:',...args)
})

Router.events.on('hashChangeComplete',(...args)=>{
    console.log('6,hashChangeComplete->hash跳转完成时,参数为:',...args)
})

// posts will be populated at build time by getStaticProps()
function Blog({ posts }) {
  return (
    <ul>
      {posts.map((post) => (
        <li>{post.title}</li>
      ))}
    </ul>
  )
}

// This function gets called at build time on server-side.
// It won't be called on client-side, so you can even do
// direct database queries. See the "Technical details" section.
export async function getStaticProps(context) {
  // Call an external API endpoint to get posts.
  // You can use any data fetching library
  const res = await fetch('https://.../posts')
  const posts = await res.json()

  // By returning { props: { posts } }, the Blog component
  // will receive `posts` as a prop at build time
  return {
    props: {
      posts,
    },
  }
}

export default Blog

function Page({ data }) {
  // Render data...
}

// This gets called on every request
export async function getServerSideProps(context) {
  // Fetch data from external API
  const res = await fetch(`https://.../data`)
  const data = await res.json()

  // Pass data to the page via props
  return { props: { data } }
}

export default Page

[name].module.css
//login.module.css
.loginli{
    color: red;
}

//修改第三方样式
.loginli :global(.active){
    color:rgb(30, 144, 255) !important;
}

import styles from './login.module.css'
<li className={styles.loginli}/>

npm i sass --save

const path = require('path')

module.exports = {
  sassOptions: {
    includePaths: [path.join(__dirname, 'styles')],
  },
}

<p style={{ color: 'red' }}>hi there</p>

function HelloWorld() {
  return (
    <li>
      Hello world
      <p>scoped!</p>
      <style jsx>{`
        p {
          color: blue;
        }
        li {
          background: red;
        }
        @media (max-width: 600px) {
          li {
            background: blue;
          }
        }
      `}</style>
      <style global jsx>{`
        body {
          background: black;
        }
      `}</style>
    </li>
  )
}

export default HelloWorld

<Head>
    <title>技术胖是最胖的！</title>
    <meta charSet='utf-8' />
</Head>