var vs let vs const (You’re Using This Wrong) | JavaScript Explained

Published: 20 April 2026
on channel: The Interview Stack

In this video, we go beyond surface-level explanations and break down the REAL reasons behind var, let, and const using:

Scope (global, function, block)
Hoisting (what JavaScript does before execution)
Temporal Dead Zone (TDZ) — the concept most people misunderstand

If you're preparing for JavaScript interviews or trying to write bug-free code, this is a must-know concept.

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WHAT YOU’LL LEARN
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Difference between var, let, and const
Why var causes unexpected bugs
Block scope vs function scope explained clearly
What hoisting actually means (not the myth)
Temporal Dead Zone (TDZ) explained simply
Why let & const throw errors before declaration
The famous for-loop + setTimeout interview question
When to use const vs let in real projects

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WHY THIS MATTERS
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This is one of the MOST ASKED JavaScript interview questions.

But more importantly — misunderstanding this leads to real production bugs.

If you're aiming for product companies or FAANG-level roles, you need more than definitions — you need mental models.

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JAVASCRIPT FUNDAMENTALS SERIES
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This is Episode 1 of a series designed to make you interview-ready with deep JavaScript understanding.

Next videos:
Closures (explained properly)
Event Loop (no confusion)
Promises & async/await
this keyword
Prototypes

Subscribe if you're serious about mastering JavaScript.

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USEFUL RESOURCES
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https://developer.mozilla.org/en-US/d...
https://developer.mozilla.org/en-US/d...
https://developer.mozilla.org/en-US/d...

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