Why error handling is required in Javascript - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to catch errors using try-catch.

Javascript

try {
  console.log('Start');
  [1]
  console.log('End');
} catch (error) {
  console.log('Error caught');
}

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

Abreak

Bconsole.log('No error')

Creturn 'Done'

Dthrow new Error('Oops!')

Attempts:

3 left

💡 Hint

Common Mistakes

Using console.log instead of throw to create an error.

The throw statement creates an error that is caught by catch.

2fill in blank

medium

Complete the code to handle errors and show a message.

Javascript

function divide(a, b) {
  try {
    if (b === 0) {
      [1]
    }
    return a / b;
  } catch (e) {
    return e.message;
  }
}

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

Areturn 'Error'

Bthrow new Error('Cannot divide by zero')

Cbreak

Dconsole.log('Divide by zero')

Attempts:

3 left

💡 Hint

Common Mistakes

Using console.log instead of throw to signal an error.

Throwing an error with a message lets the catch block handle it properly.

3fill in blank

hard

Fix the error in the code to properly catch exceptions.

Javascript

try {
  JSON.parse('invalid json');
} [1] (e) {
  console.log('Parsing failed');
}

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

Acatch

Berror

Cfinally

Dthrow

Attempts:

3 left

💡 Hint

Common Mistakes

Using error or finally instead of catch.

The catch keyword is required to catch errors thrown in try.

4fill in blank

hard

Fill both blanks to handle errors and always run cleanup code.

Javascript

try {
  let data = JSON.parse(input);
  process(data);
} [1] (err) {
  console.error('Error:', err.message);
} [2] {
  console.log('Cleanup done');
}

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

Acatch

Bfinally

Cthrow

Derror

Attempts:

3 left

💡 Hint

Common Mistakes

Using throw or error keywords incorrectly.

catch handles errors, finally runs code regardless of errors.

5fill in blank

hard

Fill all three blanks to create a function that safely parses JSON and returns null on error.

Javascript

function safeParse(jsonString) {
  try {
    return [1](jsonString);
  } [2] (e) {
    console.warn('Invalid JSON');
    return [3];
  }
}

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

AJSON.parse

Bcatch

Cnull

Dthrow

Attempts:

3 left

💡 Hint

Common Mistakes

Using throw inside catch instead of returning null.

The function tries to parse JSON. If it fails, catch runs and returns null.