The Temporal Dead Zone (TDZ) only applies to variables declared with let and const keywords in JavaScript, and not to variables declared with var.

In JavaScript, variables declared with var are hoisted to the top of their respective scopes and are initialized with a value of undefined. This means that they can be accessed and assigned before their declaration in the code.

For example:

cssCopy codeconsole.log(a); // Logs "undefined"
var a = 10;

In this code, the variable a is declared using var, and even though it's not assigned a value until the second line, it can still be accessed and will return undefined.

This is because var variables are not subject to the TDZ, and their declaration is effectively moved to the top of the scope by the JavaScript engine during runtime. This behaviour can lead to unexpected results and can make it harder to reason about the code.

Therefore, it's generally recommended to use let and const instead of var, as they provide better scoping and prevent issues such as variable hoisting and the TDZ.