Let's understand first Is hoisting applicable to both let and const?

• When using var

  At the time of memory allocation, var is initialised with undefined.

• When using let

  

  It appears that let is not being hoisted.

  But let me tell you variables declared with let and const are also hoisted. It's just that they're hoisted differently than var variables.

  Simply reading the error message reveals that it is aware that a has been declared but has not yet been initialized.

  If something is not declared, the error message will be different.

  This shows that the variables declared with let are hoisted as well. The same holds true for the const keyword.

What exactly is the Temporal Dead Zone?

The Temporal Dead Zone is defined as the time between when the const and let variables were hoisted and when they were initialized with a value.

We know that the let and const are hoisted, but they are in the Temporal Dead Zone and thus cannot be accessed before their execution.

In this code example, the Temporal Dead Zone begins when the code execution enters the console. log(a) and continues until the let a is executed.