Hello Sir/Madam,

I have one doubt regarding this question
(function fn() {
{
let a = 10;
{
var a = 20;
console.log(a);
}
}
})();

why it is giving syntax Error ?
I know this is illegal shadowing concept but when I put braces before let a =10, then that a variable has block scoped and var a is function scoped, here after adding curly braces before let a , I have create new scope and after fn(){ // here var a is
hoist}, then if both are in different scope , why it is showing error.

Please help in explaining this concept.

Thank You

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On Friday, 6 August 2021 at 11:53:53 UTC+2, gaura...@gmail.com wrote:

Hello Sir/Madam,

I have one doubt regarding this question
(function fn() {
{
let a = 10;
{
var a = 20;
console.log(a);
}
}
})();

why it is giving syntax Error ?
I know this is illegal shadowing concept but when I put braces before let a =10, then that a variable has block scoped and var a is function scoped, here after adding curly braces before let a , I have create new scope and after fn(){ // here var a is

hoist}, then if both are in different scope , why it is showing error.

They are not in a different scope: "let a" is in the *top* block scope of the function, which is the entire function, but so is "var a", as that's how var scoping works.

Please help in explaining this concept.

Have a read through this and related: <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/let>
The very last example is your case.

HTH,

Julio

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