Promise vs Callback — JS Technical Interview Questions & Answers

Side-by-side comparison table.

Promise vs Callback

  • Promise vs Callback (diff) is a JS topic. In plain words you use it for add(a, b) in a checkout total. Don’t start with a slogan — start with that picture.
  • Smallest example: function add / const add = () =>. Type it, run it, and say what you see. If you can do that from memory, you know Promise vs Callback (diff).
  • From the example next to this theory: Side-by-side comparison table.
  • Trap: this surprise in arrow vs function. Fix that before you talk about advanced JS.
  • Viva: what is Promise vs Callback (diff)? Then show function add / const add = () =>. Then name the trap.

Technical Interview Tip: What is Promise vs Callback (diff)? Show this: function add / const add = () =>. Trap: this surprise in arrow vs function.

Code Examples for Promise vs Callback

Promise vs Callback — working example

function delay(ms, value) {
  return new Promise((resolve) => setTimeout(() => resolve(value), ms));
}

async function run() {
  const a = await delay(20, "A");
  const all = await Promise.all([delay(10, 1), delay(10, 2)]);
  console.log(a, all);
}

run();

Promise vs Callback — promises represent future values; async/await is sugar. Promise.all waits for every success.

How to Explain Promise vs Callback to an Interviewer

What is Promise vs Callback (diff)?

Used for add(a, b) a checkout total Not just the heading

Give one small example of Promise vs Callback (diff).

function add / const add = () => Side-by-side comparison table

What mistake do beginners make with Promise vs Callback (diff)?

this surprise in arrow vs function Show the fix

Where do you use Promise vs Callback (diff)?

a checkout total add(a, b)