读取本地文件

getTxt() {
                var xhr = new XMLHttpRequest();
                xhr.open("get", "a.txt", true);
                xhr.send();
                xhr.onreadystatechange = function() {
                    if(xhr.readyState == 4 && xhr.status == 200) {
                        console.log(xhr, '本地对象');
                        console.log(xhr.responseText, 'txt内容');
                    } else if(xhr.status == 404) {
                        console.log(xhr.status, '23333333');
                    }
                };
    },