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利用promise及参数解构封装ajax请求的方法
目录
- 1.前端代码
- 2.后端代码
- 3.注：
1.前端代码
<!DOCTYPE html><html lang="en"><head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Document</title></head><body> <script> /** * type: get/post * url: http://localhost:3000 http://localhost:3000/details http://localhost:3000/users * data: lid=5 / uname=lili&upwd=123456 * dataType: "" / "json", 如果服务端返回的是json格式字符串，就通过dataType通知ajax函数自动转换为对象 * **/ ajax({ type: "get", url: "http://localhost:3000", dataType: "json" }) // data 不写在解构时值默认为 data: undefined ajax({ type: "get", url: "http://localhost:3000/details", data: "lid=0", dataType: "json" }) ajax({ type: "post", url: "http://localhost:3000/users", data: "uname=lili&upwd=123456", }).then(function(res){ alert(res) }) // dataType 不写在解构时值默认为 dataType: undefined function ajax({type, url,data, dataType}){ return new Promise(function(open){ var xhr = new XMLHttpRequest() xhr.onreadystatechange = function(){ if(xhr.readyState === 4 && xhr.status === 200){ if(dataType === "json"){ var res = JSON.parse(xhr.responseText) }else{ var res = xhr.responseText } console.log(res) open(res) } } if(type === "get" && data !== undefined){ url += `?${data}` } xhr.open(type, url, true) xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded") if(type === "get"){ xhr.send() }else{ xhr.send(data) } }) } </script></body></html>另：ajax实际代码实现如下
<!DOCTYPE html><html lang="en"><head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Document</title></head><body> <script> var xhr = new XMLHttpRequest() xhr.onreadystatechange = function(){ if(xhr.readyState === 4 && xhr.status === 200){ console.log(xhr.responseText) } } xhr.open("get", "http://localhost:3000", true) xhr.send() </script></body></html>2.后端代码
1) 创建一个后端项目
2) 在routes下创建index.js,users.js，代码如下
// index.jsvar express = require("express");var router = express.Router();/* GET home page. */var products = [ { lid:1, pname:"笔记本", price:3400 }, { lid:2, pname:"手机", price:5400 }, { lid:3, pname:"iPad", price:6400 }]router.get("/", function(req, res, next) { res.send(products)});router.get("/details", function(req, res, next){ var lid = req.query.lid res.send(products[lid])})module.exports = router;// user.jsvar express = require("express");var router = express.Router();/* GET users listing. */router.post("/", function(req, res, next) { var uname = req.body.uname var upwd = req.body.upwd if(uname === "lili" && upwd === "123456"){ res.send("登陆成功") }else{ res.send({ code: 0, message: "用户名或密码错误" }) }});module.exports = router;3.注：
为避免跨域，可将前端代码和后端同时放在一个项目内，使用同一地址，再发送请求调取接口
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