封装及调用fetch

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()