I am a beginner to the nodejs. When I type the below, the code error occurs like this:
TypeError [ERR_INVALID_CALLBACK]: Callback must be a function
Since node 10, it is mandatory to pass a callback on fs.writefile()
Node.js documented the purpose for the change: https://github.com/nodejs/node/blob/master/doc/api/deprecations.md#dep0013-fs-asynchronous-function-without-callback
You could add an empty callback like this fs.writeFile('writeMe.txt', data, () => {})
you also use like this
var file2 = fs.readFileSync("./Public/n2.jpeg")
This error hit me in the face when I was doing the following;
var hello = myfunction( callme() );
rather than
var hello = myfunction( callme );
fs.writeFile(...)
requires a third (or fourth) parameter which is a callback function to be invoked when the operation completes. You should either provide a callback function or use fs.writeFileSync(...)
See node fs docs for more info.
var fs = require('fs');
fs.readFile('readme.txt', 'utf8', function(err, data) {
fs.writeFile('writemeee.txt', data, function(err, result) {
if (err) console.log('error', err);
});
});
Fs.writeFile() according to the documentation here takes ( file, data[, options]and callback ) params so your code will be like this :
var fs = require('fs');
fs.readFile('readMe.txt', 'utf8', function (err, data) {
fs.writeFile('writeMe.txt', data, function(err, result) {
if(err) console.log('error', err);
});
});