11-fs-async.js

const { readFile, writeFile } = require('fs')

console.log('start');
readFile('./content/first.txt', 'utf-8', (err, result) =>{
    if(err){
        console.log(err);
        return;
    }
    const first = result;
    readFile('./content/second.txt', 'utf-8', (err, result)=>{
        if(err){
            console.log(err);
            return;
        }
        const second = result
        writeFile('./content/result-async.txt', `Here is the result: ${first} ${second}`, (err, result)=>{
            if(err){
                console.log(err);
                return;
            }
            console.log('done with this task');
        })
    })
})
console.log('starting next task');