Front End Development Front End Development Performance & Optimization

Question 1

Which image format offers the best compression for photographs on modern web browsers?

Accepted Answer

WebP

Answer

WebP provides superior lossless and lossy compression for photos compared to JPEG and PNG, reducing file sizes significantly.

Question 2

What does 'lazy loading' mean in the context of web performance?

Accepted Answer

Deferring the loading of off-screen resources until they are needed

Answer

Lazy loading defers the loading of non-critical resources (like below-the-fold images) until they are about to enter the viewport.

Question 3

What is the purpose of minifying CSS and JavaScript files?

Accepted Answer

To reduce file size by removing whitespace and unnecessary characters

Answer

Minification removes whitespace, comments, and redundant code to reduce file sizes, resulting in faster download times.

Question 4

Which HTTP caching header tells the browser how long to cache a resource?

Accepted Answer

Cache-Control

Answer

The Cache-Control header specifies caching directives, including max-age, which tells browsers how long to store a resource.

Question 5

What is the benefit of using a Content Delivery Network (CDN) for a US-based website?

Accepted Answer

It serves assets from geographically closer servers to reduce latency

Answer

A CDN distributes content across multiple servers worldwide, serving files from the closest node to reduce latency and load times.

Front End Development Practice Test