一、封装fetch

创建fetch/index.js

import 'whatwg-fetch'import 'es6-promise'export function get(url) {    let result = fetch(url, {        credentials: 'include',        headers: {            'Access-Control-Allow-Origin': '*',            'Accept': 'application/json, text/plain, */*'        },        // 设置允许cors跨域        mode: 'cors'    });    return result;}// 将对象拼接成 key1=val1&key2=val2&key3=val3 的字符串形式function obj2params(obj) {    let result = '';    let item;    for (item in obj) {        result += '&' + item + '=' + encodeURIComponent(obj[item]);    }        if (result) {        result = result.slice(1);    }        return result;}// 发送 post 请求export function post(url, paramsObj) {    let result = fetch(url, {        method: 'POST',        credentials: 'include',        headers: {            'Accept': 'application/json, text/plain, */*',            'Content-Type': 'application/x-www-form-urlencoded'        },        body: obj2params(paramsObj)    });        return result;}

二、调用fetch

1、使用then

import {get} from '../fetch/index';get("./mock/list.json").then((res) => {            return res.json();        }).then((json)=>{            this.setState({                dataList: json.data            })        }).catch(function (err) {            console.log(err);        })

　　

二、async、await

import {get} from '../fetch/index';let login = async () => {         try {            let json = await post("#", {             password: password,             username: username           });           let data = await json.json();           console.log(data);         } catch (err) {           console.log(err)         }       }       login()