FPSC- Programmer (BS-17) - PMD High Yield - 2026 — Test 10

Correct Answer: A. The browser may store the response but must revalidate it with the server before each use
Explanation: no-store is the directive that forbids storing the response at all. This is a classic trap. ALSO KNOW (related points): • Which keyboard shortcut performs a hard reload, bypassing the cache, in Chrome or Firefox on Windows? → Ctrl + Shift + R (or Ctrl + F5) • What is the difference between the HTTP cache and the Cache Storage API? → The HTTP cache is managed automatically by the browser from headers; Cache Storage is controlled by code, typically in a service worker

Correct Answer: A. Parse HTML into the DOM and CSS into the CSSOM → build the render tree → layout → paint → composite
Explanation: Changing an element's geometry triggers layout (reflow). Changing only its color triggers repaint.

Correct Answer: D. Changing an element's width
Explanation: visibility: hidden keeps the element's space, so no layout recalculation is needed. ALSO KNOW (related points): • Which image format is widely supported by all major browsers and usually gives smaller files than JPEG or PNG? → WebP

Correct Answer: C. defer runs scripts in document order after the HTML is parsed; async runs each script as soon as it downloads, in any order
Explanation: Use defer for scripts that depend on each other or on the DOM.

Correct Answer: C. No; it runs on a single main thread with an event loop, and Web Workers provide background threads
Explanation: Long-running scripts block the user interface. ALSO KNOW (related points): • Which web font format is the most efficient and universally supported in modern browsers? → WOFF2

Correct Answer: B. A missing or invalid DOCTYPE declaration
Explanation: In quirks mode, browsers emulate old non-standard behavior, such as an IE-style box model. ALSO KNOW (related points): • What is the default root font size in major browsers? → 16px

Correct Answer: D. F12 (or Ctrl + Shift + I)
Explanation: F11 toggles full screen, and Ctrl + D bookmarks the current page. ALSO KNOW (related points): • In Safari on macOS, what must be done before the Web Inspector is available? → Enable the Develop menu (in Settings → Advanced) • Which shortcut toggles the device (responsive design) mode in Chrome or Firefox DevTools? → Ctrl + Shift + M • Which shortcut shows a page's source code in most desktop browsers? → Ctrl + U • Which internal page shows Firefox's advanced configuration preferences? → about:config • Which shortcut reopens the last closed tab in Chrome, Edge, and Firefox? → Ctrl + Shift + T • Which shortcut opens a private window in Firefox? → Ctrl + Shift + P • Which shortcut opens browser history in Chrome, Edge, and Firefox? → Ctrl + H

Correct Answer: C. Code that implements a missing modern feature in older browsers
Explanation: A transpiler (such as Babel) converts new syntax. A polyfill adds missing APIs. They are complementary. ALSO KNOW (related points): • Which website is commonly used to check which browsers support a given HTML, CSS, or JavaScript feature? → caniuse.com • Which tool automates real browsers (Chrome, Firefox, Edge, Safari) through browser-specific drivers such as chromedriver and geckodriver? → Selenium WebDriver • What does a web page that works in Chrome but breaks in Safari most likely indicate? → The page uses a feature or behavior that WebKit does not support, or supports differently • Which plugin technology reached end of life in all major browsers in 2020–2021? → Adobe Flash Player • What is WebAssembly (Wasm)? → A binary instruction format that runs at near-native speed in all major browsers • Which shortcut zooms the page back to 100% in most browsers? → Ctrl + 0

Correct Answer: C. Feature detection (checking whether an API exists) rather than User-Agent sniffing
Explanation: For example, check if ('geolocation' in navigator) before using geolocation. ALSO KNOW (related points): • What were vendor prefixes such as -webkit-, -moz-, and -ms- used for in CSS? → Experimental or non-standard implementations of CSS features in specific engines • What is a headless browser? → A browser that runs without a visible user interface, used for automated testing and scraping • What is a favicon? → The small site icon shown in browser tabs, bookmarks, and history • Which statement about browser sync, such as signing into Chrome or Firefox, is correct? → It synchronizes bookmarks, passwords, history, and settings across devices using your account

Correct Answer: D. They can intercept and modify network requests, so they need a secure origin to prevent tampering
Explanation: Service workers are the basis of Progressive Web Apps (offline support and push notifications). ALSO KNOW (related points): • In Chrome, what is the address bar called that combines URL entry with search? → Omnibox • Which statement about bookmarklets is correct? → They are bookmarks whose URL begins with javascript:, which run code on the current page • What does about:blank do? → It opens an empty page generated internally by the browser, without contacting any server