Interview Q&A / Data Structures & Algorithms

1. When should you use a Map instead of a plain object in JavaScript?

   Use a Map when keys are not just strings, when you add and remove entries often, or when you need a reliable size and insertion order. Use a plain object for fixed, string-keyed records.

   BeginnerQuick answer1 min read
2. Why does [10, 9, 1].sort() return [1, 10, 9] in JavaScript?

   By default sort converts elements to strings and compares them in dictionary order, so "10" comes before "9". Pass a comparator such as (a, b) => a - b to sort numbers numerically.

   BeginnerQuick answerCoding1 min read
3. What is a stable sort and why does it matter?

   A stable sort keeps items with equal keys in their original relative order. It matters when you sort by one field after another, such as by marks first and then keep the earlier name order for ties.

   IntermediateQuick answerCoding1 min read