Custom validation rules in Express - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the express-validator check function.

Express

const { [1] } = require('express-validator');

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

Acheck

Bvalidate

Cverify

Dassert

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'validate' or 'verify' instead of 'check'.

Forgetting to destructure the import.

The check function is imported from express-validator to define validation rules.

2fill in blank

medium

Complete the code to create a custom validator that checks if a value is an even number.

Express

check('number').custom(value => value [1] 2 === 0);

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A===

B%

C+

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using '===' instead of '%'.

Using '+' or '-' which do not check divisibility.

The modulo operator % is used to check if the number is divisible by 2 with no remainder, meaning it is even.

3fill in blank

hard

Fix the error in the custom validator to correctly reject odd numbers with an error message.

Express

check('number').custom(value => {
  if (value [1] 2 !== 0) {
    throw new Error('Number must be even');
  }
  return true;
});

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

A+

B===

C%

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using '===' instead of '%'.

Using '+' or '-' which do not check divisibility.

The modulo operator % is needed to check if the number is not divisible by 2.

4fill in blank

hard

Fill both blanks to create a custom validator that checks if a username starts with a capital letter and is at least 3 characters long.

Express

check('username').custom(value => {
  if (!(/^[2]/[1](value))) {
    throw new Error('Username must start with a capital letter');
  }
  if (value.length < 3) {
    throw new Error('Username must be at least 3 characters');
  }
  return true;
});

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

Amatch

Btest

CstartsWith

D[A-Z]

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'match' which returns an array instead of boolean.

Using 'startsWith' which does not accept regex.

Using incorrect regex pattern.

The test method checks if the string matches the regular expression /^[A-Z]/, which means it starts with a capital letter.

5fill in blank

hard

Fill all three blanks to create a custom validator that checks if an email ends with '.com' and contains '@', and throws an error if not.

Express

check('email').custom(value => {
  if (!value[1]('@')) {
    throw new Error('Email must contain @');
  }
  if (!(/\.[3]$/[2](value))) {
    throw new Error('Email must end with .com');
  }
  return true;
});

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

Aincludes

Btest

Ccom

Dmatch

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'match' instead of 'test' for regex boolean check.

Using 'startsWith' instead of 'includes' for '@'.

Incorrect regex pattern for '.com'.

The includes method checks if '@' is present. The test method checks if the string ends with '.com' using the regex /\.com$/.