const fs = require('fs');fs.readFile('./1.txt', 'utf8', (err, result1) => {console.log(result1);fs.readFile('./2.txt', 'utf8', (err, result2) => {console.log(result2);fs.readFile('./3.txt', 'utf8', (err, result3) => {console.log(result3);});});
})

运行结果