Variable Hoisting — JS Technical Interview Questions & Answers

How var/let/const declarations are hoisted differently.

Variable Hoisting

  • Variable Hoisting (js) 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 Variable Hoisting (js).
  • From the example next to this theory: How var/let/const declarations are hoisted differently.
  • Trap: var leak / const reassign. Fix that before you talk about advanced JS.
  • Viva: what is Variable Hoisting (js)? Then show let for change, const for fixed. Then name the trap.

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

Code Examples for Variable Hoisting

Variable Hoisting — working example

function demo() {
  if (true) {
    var a = 1;
    let b = 2;
    const c = 3;
    console.log(b, c);
  }
  console.log(a); // 1 — var is function-scoped
  // console.log(b); // ReferenceError — let is block-scoped
}
demo();
console.log(typeof undeclaredVar); // undefined (never declared with let/const)

Variable Hoisting — var is function-scoped and hoisted; let/const are block-scoped. Prefer const, then let.

How to Explain Variable Hoisting to an Interviewer

What is Variable Hoisting (js)?

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

Give one small example of Variable Hoisting (js).

let for change, const for fixed How var/let/const declarations are hoisted differently

What mistake do beginners make with Variable Hoisting (js)?

var leak / const reassign Show the fix

Where do you use Variable Hoisting (js)?

a cart script let total = 0