fs.writeFile(file, data[, options], callback)
fs.writeFile('1111.txt', 'Node.js', (err) => {
if (err) throw err;
console.log('文件已保存!');
});
fs.readFile(path[, options], callback)
fs.readFile('111.txt', (err, data) => {
if (err) throw err;
console.log(data);
});