抛出新的 ERR_INVALID_CALLBACK(回调);

Question

I am using Node.js v17.1.0

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And getting this error :

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Answer 1

As per the documentation on fs callback api , and the error message you are getting, you need to pass a callback to the appendFile function as it expects one as the last parameter:

   fs.appendFile('greeting.txt', `Hello ${user.username} !`, (err) => {
       if (err) throw err;
       console.log('The data was appended to greeting.txt!');
    });