11-fs-async.JS

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

readFile('./content/first.txt','utf8',(err,result) =>{
    if(err) {
        console.log(err);
        return
    }
    const first = result;
    readFile('./content/second.txt','utf8',(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(result);
        })
        
    })
})