[Solved] You have a function that reads user data asynchronously and uses an error-first... } }How should you call fetchUser to correctly handle errors and print the user's name or the error message? | Node.js

Node.js - Error Handling Patterns

You have a function that reads user data asynchronously and uses an error-first callback:

function fetchUser(id, callback) {
  if (id <= 0) {
    callback(new Error('Invalid ID'), null);
  } else {
    setTimeout(() => {
      callback(null, { id, name: 'Alice' });
    }, 50);
  }
}

How should you call fetchUser to correctly handle errors and print the user's name or the error message?

AfetchUser(1, (err, user) => { if (err) console.log(err.message); else console.log(user.name); });

BfetchUser(1, (err, user) => { if (user) console.log(user.name); else console.log(err.message); });

CfetchUser(1, (user, err) => { if (err) console.log(err.message); else console.log(user.name); });

DfetchUser(1, (err, user) => { console.log(user.name); });

Step-by-Step Solution

Solution:

Step 1: Check callback parameter order and error handling
The callback parameters must be (err, user). We check if err exists first to handle errors.
Step 2: Verify correct conditional logic
If err exists, print err.message; otherwise, print user.name. fetchUser(1, (err, user) => { if (err) console.log(err.message); else console.log(user.name); }); follows this correctly.
Final Answer:
fetchUser(1, (err, user) => { if (err) console.log(err.message); else console.log(user.name); }); -> Option A
Quick Check:
Check error first, then use user [OK]

Quick Trick: Always check error before using result in callback [OK]

Common Mistakes:

Swapping error and user parameters
Not checking error before accessing user
Ignoring error handling completely

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More Node.js Quizzes

You have a function that reads user data asynchronously and uses an error-first callback:

Step 1: Check callback parameter order and error handling

Step 2: Verify correct conditional logic

Final Answer:

Quick Check:

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