I get an error in fileSystem module while using writeFile Asynchronously - node.js

Question

I'm trying to use writeFile() inside call back function of readFile() from fileSystem module..
I'm a beginner in node.js I have been watching Youtube tutorials
const fs = require('fs');
fs.readFile('readMe.txt','utf8', function(err, data){
fs.writeFile('writeMe.txt', data);
});
console.log('Fire..');
I get an error pasted below.. I don't understand the type of this error.. can someone help me with this?
Fire..!
fs.js:128
throw new ERR_INVALID_CALLBACK();
^
TypeError [ERR_INVALID_CALLBACK]: Callback must be a function
at maybeCallback (fs.js:128:9)
at Object.writeFile (fs.js:1163:14)
at C:\Users\shahzaib laptops\Desktop\NodeJS\pathModule\fileSystem.js:6:6
at FSReqWrap.readFileAfterClose [as oncomplete] (internal/fs/read_file_context.js:53:3)

Answer 1

You can use the Following snippet to read and write file what need. You this in common and use this if u need in many place. u need to pass the filename to read and write to this method.
Else directly use the callback alone the parameter in method and jsut give the file name static as u have above.
public ReadandWriteFile(fileNameToRead, fileNameToWrite, callback) {
fs.readFile(fileNameToRead, "utf-8", (err, data) => {
if (err) { console.log(err) }
if (data) {
fs.writeFile(fileNameToWrite, data, (err) => {
if (err) { console.log(err) };
if (data) {
callback({ message: 'Successfully Written to File.' })
}
});
}
})
}

Answer 2

Add proper err handling and callback Fn. in writefile
const fs = require('fs');
fs.readFile('readMe.txt','utf8', function(err, data){
if(err) callback or return err
else{
fs.writeFile('writeMe.txt', data,'utf8', function(err2, data2){
if(err2) callback or return err2
else console.log(data2)
});
}
});
console.log('Fire..');

Answer 3

You can use promise for readFile and writeFile.
const fsPromises = require("fs").promises;
async function readAndWrite() {
let filehandle;
try {
filehandle = await fsPromises.readFile("readMe.txt");
console.log(filehandle);
let writeComleted = await fsPromises.writeFile("writeMe.txt", filehandle);
} catch {
throw new Error("something bad happened");
}
}
readAndWrite();