Front End Development Performance & Optimization Flashcards
6 cards from real Front End Development practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Front End Development Performance & Optimization flashcards as text
What is the purpose of browser caching in web performance?
Answer: To store copies of resources locally so repeat visits load faster
Browser caching stores previously downloaded resources locally, so repeat page visits can load assets from the local cache instead of re-downloading them.
Which technique reduces the number of HTTP requests by combining multiple CSS files into one?
Answer: Bundling/concatenation
Bundling (concatenation) merges multiple CSS or JS files into a single file, reducing the number of HTTP requests the browser needs to make.
What does the 'defer' attribute on a tag do differently from 'async'?
Answer: Executes the script after HTML parsing is complete, in order
Unlike async, the defer attribute guarantees scripts execute after the HTML document is fully parsed and in the order they appear.
What is the primary benefit of using CSS sprites?
Answer: Combines multiple images into one to reduce HTTP requests
CSS sprites combine multiple small images into a single image file, reducing the number of HTTP requests and improving page load speed.
Which tool would a front-end developer use to measure Core Web Vitals on a production site?
Answer: Google PageSpeed Insights
Google PageSpeed Insights reports real-world Core Web Vitals data (LCP, CLS, FID/INP) from the Chrome User Experience Report.
What does 'First Contentful Paint' (FCP) measure in web performance?
Answer: Time until the first text or image is painted on screen
FCP measures the time from page navigation start until the browser renders the first piece of DOM content (text, image, or canvas).
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