Q: How do you flatten a nested array recursively in JavaScript?

function flatten(arr) { return arr.reduce((acc, item) => acc.concat(Array.isArray(item) ? flatten(item) : item), []); }. If an item is an array, recurse. Otherwise, concatenate.

Question 1

How do you traverse the DOM recursively in JavaScript?

Accepted Answer

function traverseDOM(node, callback) { callback(node); Array.from(node.children).forEach(child => traverseDOM(child, callback)); }. Call the callback on the current node, then recurse into each child.

Question 2

How do you implement fibonacci with memoization in JavaScript?

Accepted Answer

const memo = {}; function fib(n) { if (n < 2) return n; if (memo[n]) return memo[n]; return memo[n] = fib(n-1) + fib(n-2); }. Memoization reduces time from O(2^n) to O(n).

Question 3

How do you flatten a nested array recursively in JavaScript?

Accepted Answer

function flatten(arr) { return arr.reduce((acc, item) => acc.concat(Array.isArray(item) ? flatten(item) : item), []); }. If an item is an array, recurse. Otherwise, concatenate.

Question 4

What is memoization in recursion in JavaScript?

Accepted Answer

Caching the results of expensive recursive calls. Before computing, check if the result is in the cache. If so, return it. This prevents redundant computation. For fibonacci, it reduces time from O(2^n) to O(n).

How do you traverse the DOM recursively in JavaScript?

More FAQs in Recursion Interview Questions in JavaScript

Still have questions?

Want to upskill yourself?

Small steps. Big possibilities.

Our courses are taking a Coffee break, but your curiosity shouldn't. Stay engaged with namastedev linkedin, youtube, discord and other resources while you wait.