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

GIF

Answer

BMP

Answer

TIFF

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

Loading all resources at page startup

Answer

Caching files in the browser

Answer

Compressing JavaScript files

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

To add comments for documentation

Answer

To encrypt code for security

Answer

To convert code to a different language

Question 4

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

Accepted Answer

Cache-Control

Answer

Content-Type

Answer

ETag

Answer

Last-Modified

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

It compiles the source code

Answer

It provides a database backup

Answer

It generates sitemaps automatically

Question 6

What does the 'async' attribute on a <script> tag do?

Accepted Answer

Downloads the script asynchronously without blocking HTML parsing

Answer

Delays script execution until the page loads

Answer

Executes the script before HTML parsing

Answer

Enables ES module syntax