Tell us about the Event Loop in JavaScript/browser.
Middle
259
Frontend
6388
681
Tell me about the position property in CSS. What values does it have?
Middle
216
Which CSS selectors are the most expensive for the browser?
Middle
186
Tell about this in different contexts: in object methods, in arrow functions, and in regular functions.
Middle
171
What is CORS and what is it used for?
Middle
165
Tell me about CSS selector specificity. How is it calculated? What is the most specific selector?
Middle
152
import { useState } from "react"; const usePreviousValue = (value: number) => {}; export default function App() { const [count, setCount] = useState(0); const previous = usePreviousValue(count); return ( <div className="App"> <h1>Current Value: {count}</h1> <h2>Previous: {previous ?? "-"}</h2> <button onClick={() => setCount((prev) => prev + 1)}>Click</button> </div> ); }
Middle
150
Tell me about state management: which libraries have you used, and tell me about the Redux architecture.
Middle
149
How to synchronize two browser tabs using localStorage? Talk about the storage event.
Middle
146
Tell me about ways to preserve context in JavaScript: bind, call, apply. How do they differ?
Middle
140
Tell me about the React component lifecycle and hooks (useEffect, useState, useRef, useCallback, useMemo, useLayoutEffect, etc.)
Middle
138
What types are in TypeScript that are not in JavaScript? Tell about utility types.
Middle
136
Tell me about the critical stages of browser rendering (Critical Rendering Path)
Middle
133
What is the difference between the nullish coalescing operator (??) and the logical OR (||)?
Middle
133
Tell about the pattern of lifting state up in React.
Middle
133
function debounce(callback, delay) {}
Middle
131
/** * Type a function that takes an array of objects and a key, * returns an array of objects where this key/property exists **/ const filterArrayByKey = (items, key) => { return items.filter((item) => item[key] !== undefined && item[key] !== null); };
Middle
127
Tell about the defer and async attributes in the script tag. How do they differ?
Middle
112
What is the difference between simple and complex (preflight) requests in the context of CORS?
Middle
91