Request size limits in Express - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of setting request size limits in Express?

Request size limits help protect your server from very large requests that can slow down or crash your app. They stop clients from sending too much data at once.

beginner

How do you set a request size limit for JSON bodies in Express using built-in middleware?

Use express.json({ limit: 'size' }) where 'size' is a string like '100kb' or '1mb'. Example: app.use(express.json({ limit: '100kb' })) limits JSON body size to 100 kilobytes.

beginner

What happens if a client sends a request body larger than the set limit in Express?

Express will reject the request and send an error response (usually 413 Payload Too Large). This prevents the server from processing oversized data.

beginner

Which Express middleware can you use to limit URL-encoded form data size?

Use express.urlencoded({ limit: 'size' }) to limit the size of URL-encoded form data. For example, app.use(express.urlencoded({ limit: '50kb', extended: true })) limits form data to 50 kilobytes.

beginner

Why is it important to set request size limits in a real-world Express app?

Setting limits helps keep your app safe from attacks like denial of service, avoids memory overload, and improves performance by rejecting too large requests early.

Which Express middleware option sets the maximum size for JSON request bodies?

A express.limit({ size: '100kb' })

B express.static({ maxSize: '100kb' })

C express.json({ limit: '100kb' })

D express.urlencoded({ maxLength: '100kb' })

express.json({ limit: '100kb' }) correctly sets the max size for JSON bodies.

What HTTP status code does Express usually send when a request body is too large?

A 400 Bad Request

B 413 Payload Too Large

C 404 Not Found

D 500 Internal Server Error

413 Payload Too Large is the standard response when request size exceeds limits.

Which middleware limits URL-encoded form data size in Express?

A express.urlencoded()

B express.static()

C express.json()

D express.limit()

express.urlencoded() is used to parse and limit URL-encoded form data.

Why should you set request size limits in your Express app?

A To disable JSON parsing

B To allow unlimited data uploads

C To speed up client downloads

D To protect server from large requests that can cause crashes

Limits protect the server from very large requests that can slow or crash it.

How do you set a 1MB limit for JSON bodies in Express?

A app.use(express.json({ limit: '1mb' }))

B app.use(express.json({ maxSize: 1 }))

C app.use(express.urlencoded({ limit: '1mb' }))

D app.use(express.limit({ size: '1mb' }))

express.json({ limit: '1mb' }) sets the JSON body size limit to 1 megabyte.

Explain how to set request size limits for JSON and URL-encoded data in Express and why it matters.

Think about middleware options and server safety.

Describe what happens when a client sends a request larger than the allowed size limit in Express.

Focus on server response and behavior.