In this classic interview question, a new i is created for each iteration. This new i has closure with the function in setTimeout and produces the output 0 1 2 3 4. I don't understand why a new i is initialized when it's declared with let but not when it's declared with var. That should be impossible since let doesn't allow another variable with the same name to be created. Also, since closures are created when a function is defined, shouldn't the anonymous function in setTimeout still have closure around the original i equal to 0 in the block scope? Thanks.

for (let i = 0; i < 5; i++) {
    setTimeout(function () {
        console.log(i);
    }, 1000);
}
//Output: 
//0 
//1
//2
//3
//4