Map Basics — JS Technical Interview Questions & Answers

Key-value pairs with any key type and guaranteed order.

Map Basics

  • Map Basics (js intro) is a JS topic. In plain words you use it for let total = 0 in a cart script. Don’t start with a slogan — start with that picture.
  • Smallest example: let for change, const for fixed. Type it, run it, and say what you see. If you can do that from memory, you know Map Basics (js intro).
  • From the example next to this theory: Key-value pairs with any key type and guaranteed order.
  • Trap: var leak / const reassign. Fix that before you talk about advanced JS.
  • Viva: what is Map Basics (js intro)? Then show let for change, const for fixed. Then name the trap.

Technical Interview Tip: What is Map Basics (js intro)? Show this: let for change, const for fixed. Trap: var leak / const reassign.

Code Examples for Map Basics

Map Basics — working example

const scores = new Map([
  ["Ada", 10],
  ["Lin", 8],
]);
scores.set("Ada", 11);
console.log(scores.get("Ada"), scores.has("Lin"), scores.size);
scores.delete("Lin");
console.log([...scores.keys()]);

Map Basics — map keeps insertion-ordered key→value pairs; keys can be any type (unlike plain objects).

How to Explain Map Basics to an Interviewer

What is Map Basics (js intro)?

Used for let total = 0 a cart script Not just the heading

Give one small example of Map Basics (js intro).

let for change, const for fixed Key-value pairs with any key type and guaranteed order

What mistake do beginners make with Map Basics (js intro)?

var leak / const reassign Show the fix

Where do you use Map Basics (js intro)?

a cart script let total = 0