JSON获取

/* JSON.parse() 把一个标准的json字符串转化为json对象 */
        function getJson() {
            var box = document.getElementById('box');
            var str = '';
            var xhr = new XMLHttpRequest();
            xhr.open('GET', 'pubu.json', true);
            xhr.send();
            xhr.onreadystatechange = function () {
           /* 判断接口是否成功的状态 */
                if (xhr.readyState == 4 && xhr.status == 200) {
                    var lu = JSON.parse(xhr.responseText);
                    var data = lu.data;
                    var meta = lu.meta;
           /* 判断数据是否正确的状态 */
                    if (meta.status != 200) {
                        alert(meta.msg);
                        return;
                    }
                    for (var i = 0; i < data.length; i++) {
                        str = str +
                            `
                        <div class="item">
                            <img src="${data[i].imgUrl}">
                            <div>${data[i].title}</div>
                        </div>
                        `
                    }
                    box.innerHTML = str;
                }
            }
        }
    </script>
    ```