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Kenil Vasani
Kenil Vasani

Kenil Vasani

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Asked: 2020-12-22T07:07:33+00:00

how to fix this error TypeError [ERR_INVALID_CALLBACK]: Callback must be a function

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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

var fs = require('fs');
fs.readFile('readMe.txt', 'utf8', function (err, data) {
  fs.writeFile('writeMe.txt', data);
});
callbacknode.js
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    1 Answer

    1. Kenil Vasani

      Kenil Vasani

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      Best Answer

      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);
   });
 });
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