Function Declaration vs Expression — JS Technical Interview Questions & Answers

Hoisting and naming differences.

Function Declaration vs Expression

  • Function Declaration vs Expression (js) 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 Function Declaration vs Expression (js).
  • From the example next to this theory: Hoisting and naming differences.
  • Trap: this surprise in arrow vs function. Fix that before you talk about advanced JS.
  • Viva: what is Function Declaration vs Expression (js)? Then show function add / const add = () =>. Then name the trap.

Technical Interview Tip: What is Function Declaration vs Expression (js)? Show this: function add / const add = () =>. Trap: this surprise in arrow vs function.

Code Examples for Function Declaration vs Expression

Function Declaration vs Expression — working example

function greet(name = "friend") {
  return "Hi " + name;
}
const shout = function (msg) {
  return msg.toUpperCase();
};
(function () {
  console.log("IIFE ran");
})();

function mapNums(nums, fn) {
  const out = [];
  for (const n of nums) out.push(fn(n));
  return out;
}
console.log(greet("Ada"), shout("js"));
console.log(mapNums([1, 2], (n) => n * 2));

function factorial(n) {
  if (n <= 1) return 1;
  return n * factorial(n - 1);
}
console.log(factorial(4));

Function Declaration vs Expression — functions take parameters, can be expressions/IIFEs/callbacks, and recurse with a base case. Pure functions avoid side effects.

How to Explain Function Declaration vs Expression to an Interviewer

What is Function Declaration vs Expression (js)?

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

Give one small example of Function Declaration vs Expression (js).

function add / const add = () => Hoisting and naming differences

What mistake do beginners make with Function Declaration vs Expression (js)?

this surprise in arrow vs function Show the fix

Where do you use Function Declaration vs Expression (js)?

a checkout total add(a, b)