Hoisting inside Function

Question

Can someone explain below code:

What will be the value of myVar inside function b?

function a() {
        function b() {
            console.log("b", myVar); 
        }
        b();
    let myVar;    
    console.log("a", myVar);  //Look for a execution context
}
a();

It never gets initialized - it never gets a value, and is accessed before initialization, so it throws. — CertainPerformance, Mar 11 '19 at 08:26
`let` is different to `var` - see the [temporal dead zone](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/let#Temporal_dead_zone) - which is not a Stephen King short story — Jaromanda X, Mar 11 '19 at 08:31
@CertainPerformance, Isn't the myVar should be hoisted to the top inside function "a" and as b function is sitting lexically inside "a" function it should look to its upper scope(i.e parent "a") — Dolly, Mar 11 '19 at 08:36

score 0 · Answer 1 · answered Mar 11 '19 at 08:36

0

let variables are not initialized until their definition is evaluated. Accessing the variable before the initialization results in a ReferenceError

answered Mar 11 '19 at 08:36

Himanshu Pandey

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Isn't the myVar should be hoisted to the top inside function "a" and as "b" is sitting lexically inside "a" function it should look to its upper scope(i.e parent "a") – Dolly Mar 11 '19 at 08:38
no, myVar are hoisted but period between entering scope and being declared where they cannot be accessed. This period is the temporal dead zone (TDZ). https://stackoverflow.com/questions/33198849/what-is-the-temporal-dead-zone – Himanshu Pandey Mar 11 '19 at 08:42

score 0 · Answer 2 · answered Aug 25 '20 at 08:16

Declare myVar to var instead fo let. it will give you undefined. So it is a simple concept of Keyword let not concept of Hoisting inside a function. Run only the below code. you will get the same error.

console.log(number); //Reference error
let number= 1;

Hoisting inside Function

2 Answers2