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; 
        }
        // console.log(result);
    });

    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');