util.promisify(original)

const fs = require("fs");
// 改造现有异步函数api 让其返回promise对象 从而支持异步函数语法
const promisify = require("util").promisify;
// 调用promisify方法改造现有异步API 让其返回promise对象
const readFile = promisify(fs.readFile);

async function run() {
    
    
	let r1 = await readFile("./1.txt", "utf8");
	let r2 = await readFile("./2.txt", "utf8");
	let r3 = await readFile("./3.txt", "utf8");
	console.log(r1);
	console.log(r2);
	console.log(r3);
}

run();