JavaScript - Temporal Dead Zone (TDZ)

Overview

Estimated time: 10–15 minutes

The Temporal Dead Zone (TDZ) is the period between entering scope and variable declaration with let or const.

Learning Objectives

• Understand what the TDZ is and why it exists.
• Recognize errors caused by accessing variables in the TDZ.

Prerequisites

• JavaScript - Execution Context & Lexical Scope

TDZ Example

console.log(a); // ReferenceError
let a = 3;

Common Pitfalls

• TDZ only applies to let and const, not var.

Summary

The TDZ helps catch bugs by preventing access to variables before declaration.