React本身不包含发送Ajax的代码，一般使用第三方的库。如axios，这是专门用于ajax请求的库。其封装了XmlHttpRequest对象的ajax,且使用promise风格写法，在浏览器的客户端与服务端都能使用。
你可能会想问为什么不用fetch()原生函数呢？因为考虑到对老版本浏览器的支持情况。 其次，fetch（）不使用XmlHttpRequest对象发生ajax请求。
如果你想使用fetch()在低版本浏览器中，你可以考虑使用fetch.js的兼容库。
[axios CDN]
代码语言：javascript复制https://cdn.bootcss.com/axios/0.18.0/axios.js//get方式
代码语言：javascript复制axios.get(url)
.then(response=>{
})
.catch(error =>{
console.log(error.message)
})//post方式
代码语言：javascript复制axios.post(url,{参数对象})
.then(response=>{
console.log(response)
})
.catch(error =>{
console.log(error.message)
})示例：
代码语言：javascript复制<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
</head>
<body>
<div id="test"></div>
<script src="https://cdn.bootcss.com/react/16.4.0/umd/react.development.js"></script>
<script src="https://cdn.bootcss.com/react-dom/16.4.0/umd/react-dom.development.js"></script>
<script src="https://cdn.bootcss.com/axios/0.17.1/axios.js"></script>
<script src="https://cdn.bootcss.com/babel-standalone/6.26.0/babel.min.js"></script>
<script type="text/babel">
class MostStar extends React.Component {
state = {
repoName:'',
repoUrl: ''
}
componentDidMount() {
//方式1、使用axio发送异步ajax请求
const url = 'https://api.github.com/search/repositories?q=tetris language:assembly&sort=stars&order=desc'
axios.get(url)
.then(response => {
const result = response.data;
const {name,html_url} = result.items[0];
this.setState({repoName:name,repoUrl:html_url});
})
//方式2、使用fetch()发生请求
fetch(url)
.then(response => {
return response.json()
})
.then(data=>{
//得到数据
const {name,html_url} = data.items[0];
this.setState({repoName:name,repoUrl:html_url});
})
}
render() {
const {repoName,repoUrl} = this.state
if(!repoName){
return (
<h2>Loading...</h2>
)
}else {
return (
<h2>Most star repo is <a href={repoUrl}>{repoName}</a></h2>
)
}
}
}
ReactDOM.render(<MostStar/>,document.getElementById('test'))
</script>
</body>
</html>使用fetch发生请求
fetch使用文档
代码语言：javascript复制https://www.bootcdn.cn/fetch/readme/
https://segmentfault.com/a/1190000003810652用法
代码语言：javascript复制fetch(url).then(function(response){
return response.json()
}).then(function(data){
console.log(data);//这才是返回的数据
}).catch(function(e){
console.log(e);
})练习:写一个搜索请求##
- 1、初始化react-app
- 2、拆分组件
- 3、编写静态组件
- 4、编写动态组件
index.js
代码语言：javascript复制import React from 'react';
import ReactDOM from 'react-dom';
import './components/index.css';
import App from './components/app';
ReactDOM.render(<App />, document.getElementById('root'));app.jsx
代码语言：javascript复制import React, { Component } from 'react'
import Search from './search'
import Main from './main'
class App extends Component {
state = {
searchName: ''
}
//更新状态
setSearchName = (searchName) => this.setState({searchName})
render () {
return (
<div className="container">
<Search setSearchName={this.setSearchName}/>
<Main searchName={this.state.searchName}/>
</div>
)
}
}
export default Appsearch.jsx
代码语言：javascript复制import React, { Component } from 'react'
import PropTypes from 'prop-types'
class Search extends Component {
static propTypes = {
setSearchName: PropTypes.func.isRequired
}
handleSearch = () => {
//得到输入的关键字
const searchName = this.input.value.trim();
if(searchName){
//搜索
this.props.setSearchName(searchName);
}
}
render () {
return (
<section className="jumbotron">
<h3 className="jumbotron-heading">Search Github Users</h3>
<div>
<input type="text" placeholder="enter the name you search" ref={input=>this.input=input}/>
<button onClick={this.handleSearch}>Search</button>
</div>
</section>
)
}
}
export default Searchmain.jsx
代码语言：javascript复制import React, { Component } from 'react'
import PropTypes from 'prop-types'
import axios from 'axios'
class Main extends Component {
static propTypes = {
searchName: PropTypes.string.isRequired
}
state = {
initView: true,
loading: false,
users: null,
errorMsg: null
}
//当组件接收到新的属性时进行回调
componentWillReceiveProps(newProps) {//指定新的searchName,需要发请求
const {searchName} = newProps;
//更新状态
this.setState({
initView:false,
loading:true
})
//发请求
const url = `https://api.github.com/search/users?q=${searchName}`;
axios.get(url)
.then(response => {
//得到数据
const result = response.data;
const users = result.items.map(item=> {
return {name:item.login,url:item.html_url,avatarUrl:item.avatar_url}//注意
})
//更新状态
this.setState({
loading:false,
users
})
})
.catch(error => {
//更新状态
this.setState({
loading:false,
errorMsg:error.message
})
})
}
render () {
const {initView,loading,users,errorMsg} = this.state;
const {searchName} = this.props;
if(initView){
return <h2>请输入关键词进行搜索:{searchName}</h2>
}else if(loading){
return <h2>正在请求</h2>
}else if(errorMsg){
return <h2>{errorMsg}</h2>
}else {
return (
<div className="row">
{
users.map((user,index)=>(
<div className="card" key={index}>
<a href={user.url} target="_blank">
<img src={user.avatarUrl} style={{width: 100}}/>
</a>
<p className="card-text">{user.name}</p>
</div>
))
}
</div>
)
}
}
}
export default Mainindex.css
代码语言：javascript复制.album {
min-height: 50rem; /* Can be removed; just added for demo purposes */
padding-top: 3rem;
padding-bottom: 3rem;
background-color: #f7f7f7;
}
.card {
float: left;
width: 33.333%;
padding: .75rem;
margin-bottom: 2rem;
border: 1px solid #efefef;
text-align: center;
}
.card > img {
margin-bottom: .75rem;
border-radius: 100px;
}
.card-text {
font-size: 85%;
}
