Answer :
Explanation :

Error-first callbacks are used to pass errors and data as well. You have to pass the error as the first parameter, and it has to be checked to see if something went wrong. Additional arguments are used to pass data.   fs.readFile(filePath, function(err, data) { if (err) { // handle the error, the return is important here // so execution stops here return console.log(err) } // use the data object console.log(data)})