Question title seems straight forward but that's not what I am asking. Please try following examples
for(let i=0; i<5; i++){
//console.log(i);
let i=5
console.log(i);
}This example works and my question is how is it possible to declare another variable with same identifier inside for loop.
I am really confused, what is going on??
For the semantics of let in for loops, see Explanation of `let` and block scoping with for loops.
How is it possible to declare another variable with same identifier inside
forloop?
It's because your for loop has a block statement as its body, and in there you can declare your own block-scoped variables, shadowing the ones from parent scopes.
In the following example you set the value of i to 5 so the loop ends coz that's the condition for the loop i<5. So condition is false for the loop to run again
for(let i=0; i<5; i++){
//console.log(i);
i=5
console.log(i);
}And in your firs example, loop continues coz let i =5 is considered a separate variable in the for loop scope
I think below code will remove all your doubt It is all about scope, You can not re-define same variable in same scope but you can define in nested scope
Same thing happening in your code for has own scope and inside for means
for { //inside this } is nested scope of `for`.
{
let a = "a";
console.log(a);
{
let a = "b";
console.log(a);
}
console.log(a);
}
var, let and const.It seems like a lot of people are talking around the real point of confusion here...
Ok, so when you say
// scope A
for(let i = 0; i<5; i++) {
//scope B
}
we know i is not declared in Scope A. (That's one of the big problems let solves.) So it seems it must be declared in Scope B. But what about this case?
// scope A
for(let i = 0; i<5; i++) console.log(i);
The for loop still has to have its own scope, in order to keep i from being in Scope A. And we can demonstrate this.
let i = 37;
for(let i = 0; i < 5; i++) console.log(i);
console.log(i); // prints 37
Now if the for statement already has a scope even though it has no braces, then what happens when we replace console.log(i) with a block statement? Well, that block statement gets its own scope. So really we have
// Scope A
for( //scope B is actually here
let i = 0; i < 5; i++) {
// Scope C
}
