Manual validation patterns in Express - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import Express and create an app instance.

Express

const express = require('[1]');
const app = express();

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Aexpress

Bhttp

Cfs

Dpath

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'http' instead of 'express' for the require statement.

Forgetting to require the Express module.

You need to import the 'express' module to create an Express app.

2fill in blank

medium

Complete the code to add a middleware that parses JSON bodies.

Express

app.use(express.[1]());

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Ajson

Burlencoded

Cstatic

Dtext

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'urlencoded' middleware instead of 'json' for JSON bodies.

Not adding any middleware to parse request bodies.

Use express.json() middleware to parse JSON request bodies.

3fill in blank

hard

Fix the error in the validation middleware to check if 'age' is a number.

Express

app.post('/submit', (req, res) => {
  const age = req.body.age;
  if (typeof age !== '[1]') {
    return res.status(400).send('Age must be a number');
  }
  res.send('Valid age');
});

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Astring

Bboolean

Cnumber

Dobject

Attempts:

3 left

💡 Hint

Common Mistakes

Checking for 'string' type instead of 'number'.

Using 'typeof age === number' without quotes.

Use typeof age === 'number' to check if age is a number.

4fill in blank

hard

Fill both blanks to validate that 'email' exists and contains '@'.

Express

app.post('/register', (req, res) => {
  const email = req.body.email;
  if (!email || !email[1]('@')) {
    return res.status(400).send('Invalid email');
  }
  res.send('Email valid');
});

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AindexOf

Bincludes

CstartsWith

DendsWith

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'startsWith' or 'endsWith' which only check start or end of string.

Using 'indexOf' but forgetting to check for -1.

Use email.includes('@') to check if the email contains '@'.

5fill in blank

hard

Fill both blanks to validate 'username' length and characters.

Express

app.post('/user', (req, res) => {
  const username = req.body.username;
  if (!username || username.length < [1] || !/^[a-zA-Z0-9]+$/.[2](username)) {
    return res.status(400).send('Invalid username');
  }
  res.send('Username valid');
});

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A3

Btest

Cmatch

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'match' instead of 'test' for regex validation.

Checking length with wrong number.

Check username length is at least 3 and use regex test method to validate characters.