Promise实践联系-ajax模块.html

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="//code.jquery.com/jquery-1.10.2.js"></script>
    <script src="./data//content.txt"></script>
</head>

<body>
    <h2>Promise AJAX 操作</h2>
    <button id="btn">点击发送AJAX</button>
    <script>
        const btn = document.querySelector('#btn');
        btn.addEventListener('click', function () {
            //创建Promise
            const p = new Promise((resolve, reject) => {
                //1. 创建对象
                const xhr = new XMLHttpRequest();
                //2. 初始化
                xhr.open('GET', './data/content.txt');
                //3.发送
                xhr.send()
                //4. 处理响应结果
                xhr.onreadystatechange = function () {
                    if (xhr.readyState === 4) {
                        //判断响应状态码 2xx表示成功
                        if (xhr.status >= 200 && xhr.status < 300) {
                            //输出响应结果
                            resolve(xhr.response)
                        } else {
                            //控制台输出状态码
                            reject(xhr.status)
                        }
                    }
                }
            })
            console.log(p)
            p.then((data) => {
                console.log(data)
            }, (code) => {
                console.log(code)
            })
        })
    </script>
</body>

</html>