初始印象版：简单的封装一个axios请求（GET\POST\PUT\DELETE）

- 日理万妓 2023-06-17 08:54 8阅读 0赞

### 注意：       要想点击看到效果，请阅读以下两篇文章，就知道怎么弄数据了。       [https://blog.csdn.net/JEFF\_luyiduan/article/details/103226648][https_blog.csdn.net_JEFF_luyiduan_article_details_103226648]       [https://blog.csdn.net/JEFF\_luyiduan/article/details/103234020][https_blog.csdn.net_JEFF_luyiduan_article_details_103234020] ###

<!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>
            <button onclick="testGet()">GET请求</button>
            <button onclick="testPOST()">POST请求</button>
            <button onclick="testPUT()">PUT请求</button>
            <button onclick="testDELETE()">DELETE请求</button>
        </div>
    </body>
    <script>
        // GET：从服务器端读取数据
        function testGet() {
            axios({
                url: 'http://localhost:3000/posts',
                method: 'GET',
                params: {
                    id: '1',
                    xyz: 'lm'
                }
            }).then(
                response => {
                    console.log(response)
                },
                error => {
                    console.log(error.message)
                }
            )
        }
        // POST：向服务器端添加新数据,效果在db.json文件里面查看
        function testPOST() {
            axios({
                url: 'http://localhost:3000/posts',
                method: 'POST',
                data: {
                    "title": "post添加或者保存数据",
                    "author": "Flintstone",
                }
            }).then(
                response => {
                    console.log(response)
                },
                error => {
                    console.log(error.message)
                }
            )
        }
        // PUT：更新服务器端已经存在的数据,效果在db.json文件里面查看
        function testPUT() {
            axios({
                url: 'http://localhost:3000/posts/1',
                method: 'put',
                data: {
                    title: 'post测试已被put更新',
                    author: 'Flintstone'
                }
            }).then(
                response => {
                    console.log(response)
                },
                error => {
                    console.log(error.message)
                }
            )
        }
        //DELETE：删除服务器端数据,效果在db.json文件里面查看
        function testDELETE() {
            axios({
                url: 'http://localhost:3000/posts/1',
                method: 'delete',
            }).then(
                response => {
                    console.log(response)
                },
                error => {
                    console.log(error.message)
                }
            )
        }
    
    
        /*
            1函数的返回值为 promise，成功的结果为 response，异常的结果为eror
            2.能处理多和类型的请求:GET/POST/PUT/ DELETE
            3，函数的参数为一个配置对象
                {
                    url:'', 	//请求地址
                    method:'',	//请求方式GET/POST/PUT/ DELETE
                    params:{},	//GET/ DELETE请求的 query参数
                    data:{},	//POST或 DELETE请求的请求体参数
                }
            4.响应json数据自动解析为js
        */
        function axios({
            url,
            method = 'GET',
            params = {},
            data = {}
        }) {
            //返回一个promise对象
            return new Promise((resolve, reject) => {
                //处理method(转大写)
                method = method.toUpperCase()
    
                //处理query参数（拼接到url上） id=1&xyz=lm
                /*
                    {
                        id = 1 ,
                        xyz = 'lm'
                    }
                */
                let queryString = ''
                Object.keys(params).forEach(key => {
                    queryString += `${key}=${params[key]}&`
                })
                if (queryString) {//id=1&xyz=lm
                    //去除最后的&
                    queryString = queryString.substring(0, queryString.length - 1)
                    //接到url
                    url += '?' + queryString
                }
    
                //1.执行一步ajax请求
                //创建xhr对象
                const request = new XMLHttpRequest()
                //打开连接（初始化请求）
                request.open(method, url, true)
                //绑定状态改变的监听
                request.onreadystatechange = function () {
                    //如果没有完成，直接结束
                    if (request.readyState !== 4) {
                        return
                    }
                    //如果响应状态码在[200,300]之间代表成功，否则失败
                    const { status, statusText } = request
                    //2.1 如果请求成功了，调用resolve()
                    if (status >= 200 && status <= 299) {
                        //准备结果数据对象response
                        const response = {
                            data: JSON.parse(request.response),
                            status,
                            statusText
                        }
                        resolve(response)
                    } else {
                        //2.2如果请求失败了，调用reject()
                        reject(new Error('request error status is ' + status))
                    }
                }
                //发送请求
                if (method === 'GET' || method === 'DELETE') {
                    request.send()
                } else if (method === 'POST' || method === 'PUT') {
                    request.setRequestHeader('Content-Tyep', 'application/json;charset=utf-8')//告诉服务器请求体的格式是json
                    request.send(JSON.stringify(data))//发送json格式请求体参数
                }
    
                //2.1.如果请求成功了，调用resolve()
    
                //2.2.如果请求失败了，调用reject()
    
    
            })
        }
    </script>
    
    </html>

[https_blog.csdn.net_JEFF_luyiduan_article_details_103226648]: https://blog.csdn.net/JEFF_luyiduan/article/details/103226648
[https_blog.csdn.net_JEFF_luyiduan_article_details_103234020]: https://blog.csdn.net/JEFF_luyiduan/article/details/103234020