LinkedIn Frontend Engineer Interview Questions

To provide an optimized news feed experience, LinkedIn needs to find the maximum engagement scores among k updates shared by users in real-time.
Given an array of integers representing engagement scores for the updates, return an array of maximum scores for each sliding window of size k.Function Signature:
- function maxSlidingWindow(scores: number[], k: number): number[]Example 1:
Input: scores = [1, 3, -1, -3, 5, 3, 6, 7], k = 3
Output: [3, 3, 5, 5, 6, 7]
Explanation: The maximum of the first three scores is 3, then 5 for the next window, and so forth.Example 2:
Input: scores = [1, -1], k = 1
Output: [1, -1]
Explanation: Each element is its own maximum in a window of size 1.Constraints:
- 1 <= scores.length <= 10^5
- -10^4 <= scores[i] <= 10^4
- 1 <= k <= scores.length

LinkedIn's frontend applications require efficient data fetching and rendering without blocking the UI thread.
Given an array of integers representing taskDurations (in milliseconds) for asynchronous tasks, simulate the behavior of the event loop to determine the total time taken to complete all tasks and print them in the order they finish. You may assume a maximum concurrency of n (number of simultaneous tasks).Function Signature:
- function simulateEventLoop(taskDurations: number[], n: number): numberExample 1:
Input: taskDurations = [200, 100, 300], n = 2
Output: 400
Explanation: The first two tasks run concurrently (200ms, 100ms), taking 200ms, followed by the 300ms task which starts after the 100ms task completes.Example 2:
Input: taskDurations = [300, 100, 200, 400], n = 2
Output: 700
Explanation: The first two tasks (300ms and 100ms) complete in 300ms, followed by 200ms starting, and then 400ms which completes after.Constraints:
- 1 <= taskDurations.length <= 1000
- 1 <= taskDurations[i] <= 10^4
- 1 <= n <= 100

For LinkedIn's notification system, we need to design a Debounced EventEmitter that prevents rapid firing of events when notifications are updated. The debounce should wait a specified time period before invoking the callback for the latest event.Class Signature:
- class DebouncedEventEmitter {
- emit(event: string, data: any): void;
- on(event: string, callback: Function): void;
- constructor(delay: number);
- }Example 1:
- Initialize an event emitter with a 200ms debounce: const emitter = new DebouncedEventEmitter(200).
- Call emitter.on('notify', (data) => console.log(data)); and emitter.emit('notify', 'You have a new message!'), it should log once after 200ms of inactivity.Constraints:
- The debounce should correctly handle multiple calls to emit within the specified delay.

With the requirement of an efficient and performant navigation system within LinkedIn's Single Page Application (SPA), design a client-side router that will help manage the navigation state and URL changes without refreshing the entire page.Class Signature:
- class Router {
- constructor(routes: Map<string, Function>);
- navigate(url: string): void;
- on(url: string, handler: Function): void;
- }Example 1:
- Initialize a Router with routes: const router = new Router(new Map([['/', () => 'Home'], ['/profile', () => 'Profile']]))
- Call router.navigate('/') should call the handler for home and update the view accordingly.Constraints:
- The Router should ensure that handlers for routes are invoked in order and each URL is associated with a specific view.
- Only allow paths as keys in the routes Map.
- Max 100 routes can be registered at a time.