Front End Development Front End Development Performance & Optimization 3

Question 1

What is the purpose of browser caching in web performance?

Accepted Answer

To store copies of resources locally so repeat visits load faster

Answer

Browser caching stores previously downloaded resources locally, so repeat page visits can load assets from the local cache instead of re-downloading them.

Question 2

Which technique reduces the number of HTTP requests by combining multiple CSS files into one?

Accepted Answer

Bundling/concatenation

Answer

Bundling (concatenation) merges multiple CSS or JS files into a single file, reducing the number of HTTP requests the browser needs to make.

Question 3

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

Accepted Answer

Executes the script after HTML parsing is complete, in order

Answer

Unlike async, the defer attribute guarantees scripts execute after the HTML document is fully parsed and in the order they appear.

Question 4

What is the primary benefit of using CSS sprites?

Accepted Answer

Combines multiple images into one to reduce HTTP requests

Answer

CSS sprites combine multiple small images into a single image file, reducing the number of HTTP requests and improving page load speed.

Question 5

Which tool would a front-end developer use to measure Core Web Vitals on a production site?

Accepted Answer

Google PageSpeed Insights

Answer

Google PageSpeed Insights reports real-world Core Web Vitals data (LCP, CLS, FID/INP) from the Chrome User Experience Report.

Front End Development Practice Test

Front End Development Practice Test

Front End Development Front End Development Performance & Optimization 3