Why robust error handling matters in Node.js - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to catch errors in an async function.

Node.js

async function fetchData() {
  try {
    const response = await fetch('https://api.example.com/data');
    const data = await response.json();
    return data;
  } catch ([1]) {
    console.error('Error fetching data:', error);
  }
}

Drag options to blanks, or click blank then click option'

Aerr

Bexception

Ce

Derror

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different variable name in catch than inside the block.

The catch block uses the variable error to hold the caught error. This variable is then used inside the block.

2fill in blank

medium

Complete the code to throw a custom error when a condition fails.

Node.js

function checkAge(age) {
  if (age < 18) {
    throw new [1]('Age must be at least 18');
  }
  return true;
}

Drag options to blanks, or click blank then click option'

AException

BError

CTypeError

DRangeError

Attempts:

3 left

💡 Hint

Common Mistakes

Using non-existent error classes like Exception.

Throwing a new Error object is the standard way to create custom errors in JavaScript.

3fill in blank

hard

Fix the error in the code to properly handle errors in a promise chain.

Node.js

fetch('https://api.example.com/data')
  .then(response => response.json())
  .then(data => console.log(data))
  .catch([1] => console.error('Fetch error:', err));

Drag options to blanks, or click blank then click option'

Aerr

Be

Cerror

Dexception

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different variable name than inside the catch function.

The catch block uses err as the parameter, which matches the variable used inside the arrow function.

4fill in blank

hard

Fill both blanks to create a try-catch block that logs the error message and rethrows the error.

Node.js

try {
  JSON.parse('[1]');
} catch ([2]) {
  console.error([2].message);
  throw [2];
}

Drag options to blanks, or click blank then click option'

A"{ invalid json }"

Berror

Cerr

D"{ key: 'value' }"

Attempts:

3 left

💡 Hint

Common Mistakes

Using valid JSON string so no error occurs.

Mismatch between catch parameter and usage.

The string "{ invalid json }" is invalid JSON and will cause an error. The catch block uses error to log and rethrow the error.

5fill in blank

hard

Fill all three blanks to create a function that handles errors and returns a default value.

Node.js

async function getUser(id) {
  try {
    const response = await fetch(`/users/$[1]`);
    if (!response.ok) throw new Error('User not found');
    return await response.json();
  } catch ([2]) {
    console.error([2].message);
    return [3];
  }
}

Drag options to blanks, or click blank then click option'

Aid

Berror

C{}

DuserId

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong variable names in URL or catch.

Returning undefined instead of a default value.

The function uses id in the URL, catches errors with error, logs the message, and returns an empty object {} as a default value.