JavaScript

Temporal Dead Zone

Definition

The period between entering a scope and the point where a `let` or `const` variable is declared. Accessing the variable during this period throws a ReferenceError. This prevents bugs caused by using variables before they are initialized.

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Related Terms

Variable

A named container that stores a value in memory. JavaScript uses let, const, and var to declare variables. let and const are block-scoped, while var is function-scoped.

Hoisting

JavaScript's behavior of moving variable and function declarations to the top of their scope before code execution. var declarations are hoisted and initialized to undefined, while let and const are hoisted but not initialized (temporal dead zone).

Scope

The region of code where a variable is accessible. JavaScript has global scope, function scope, and block scope. Block scope was introduced with let and const in ES6.