project_03
/
xhr的使用.html

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

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="./lib/jquery.js"></script>
</head>

<body>

    <script>
        var xhr = new XMLHttpRequest();
        xhr.open('get', 'http://www.liulongbin.top:3006/api/getbooks');
        xhr.send()
            //第4步,监历hr.onreadystatechange事件,处理响应回来的结果
        xhr.onreadystatechange = function() {
            //判断请求是否成功
            if (xhr.readyState == 4 && xhr.status == 200) { // status服务器响应的状态码: 200成功, 404地址找不到
                //打印响应的结果数据
                console.log(xhr.responseText, typeof xhr.responseText);
                //当前请求响应回来的就是json字符中--转成js对象
                var data = JSON.parse(xhr.responseText)
                console.log(data);
            }
        }
    </script>
</body>

</html>