In ES6, Temporal Dead Zone is a behavior occurring in JavaScript while declaring a variable with the let and const keywords. The period between entering the scope and being declared is the one when these keywords cannot be accessed and enter the Temporal Dead Zone.

For example

console.log(foo); // undefined
var foo = 123;

console.log(foo); // Error
let foo = 123;

Also Read: JQuery Questions

If you consider that the const and let are also in place, why can't they be accessible before they are declared? The answer is within the idea of the Temporal Dead Zone.

Variables declared with let and const are stored and placed in the Temporal Dead Zone. Therefore, they cannot be accessible before the declaration is executed during the step-by-step process of scripting.

Temporal Dead Zone is the duration that let and const declarations are not accessible. Declarations of the let as well as const declarations are not accessible.

Temporal Dead Zone is activated when code execution is entered into the block that includes let or const declarations. It continues until the lets or const declaration. It continues until the declaration is executed.

BY Best Interview Question ON 24 Aug 2022