Compression middleware in Node.js - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is compression middleware in Node.js?

Compression middleware is a tool that reduces the size of HTTP responses before sending them to the client. This helps pages load faster and saves bandwidth.

beginner

How do you add compression middleware to an Express app?

You install the 'compression' package and then use it as middleware with app.use(require('compression')()). This compresses all responses automatically.

intermediate

Which compression algorithms does the 'compression' middleware support by default?

It supports gzip and deflate compression algorithms by default, choosing the best one supported by the client browser.

intermediate

Why should you be careful when compressing certain types of responses?

Some responses like images or already compressed files don't benefit from compression and can waste CPU time. Also, compressing very small responses may add overhead.

advanced

How can you control which responses get compressed using compression middleware?

You can pass a filter function to the middleware options that checks the response type or size and returns true or false to decide if compression should happen.

What does compression middleware do in a Node.js server?

A Reduces the size of HTTP responses before sending

B Encrypts the HTTP responses

C Caches the HTTP responses

D Logs the HTTP requests

Compression middleware reduces the size of HTTP responses to speed up loading and save bandwidth.

Which package is commonly used for compression middleware in Express?

A express-compress

B body-parser

C compression

D morgan

The 'compression' package is the standard middleware for compressing responses in Express.

Which compression algorithms does the 'compression' middleware support by default?

A gzip and deflate

B brotli only

C lzma and bzip2

D zip only

By default, the middleware supports gzip and deflate compression algorithms.

Why might you want to skip compressing images with compression middleware?

A Compression middleware does not work on images

B Images are already compressed and compressing again wastes CPU

C Images cannot be compressed

D Images load faster uncompressed

Images are often already compressed formats like JPEG or PNG, so compressing them again wastes CPU without much benefit.

How can you customize which responses get compressed?

A By disabling compression globally

B By changing the server port

C By modifying the request headers

D By setting a filter function in middleware options

You can provide a filter function to decide if a response should be compressed based on type or size.

Explain how compression middleware improves web performance and how to add it to an Express app.

Think about how smaller files travel faster over the internet.

Describe when and why you might want to exclude certain responses from compression.

Not all files benefit from compression equally.