what is temporal dead zone in javascript

The Temporal Dead Zone (TDZ) in JavaScript refers to the state where variables are unreachable because they are in scope but not yet declared

. A TDZ starts at the beginning of a block's local scope and ends when the computer fully initializes the variable with a value

. When a variable is accessed before its declaration, JavaScript throws a ReferenceError

. The TDZ is related to the order of execution (time) rather than the location in the code (space)

. It affects variables declared with let, const, or class

. The purpose of the TDZ is to prevent variables from being accessed before they are initialized, ensuring that their values are not undefined or inconsistent. Here's an example to illustrate the TDZ:

javascript

function printAge() {
  console.log(age);
}

const age = 20;
printAge(); // 20

In this example, the age variable is accessed before its declaration, causing a ReferenceError. However, in the following example, the age variable is accessed after its declaration, and the code works as expected:

javascript

function printAge() {
  console.log(age);
}

let age = 30;
printAge(); // Error

To avoid issues related to the TDZ, it's essential to access variables from outside the TDZ or to ensure that they are initialized with a value before being accessed