ECMAScript 6's let is supposed to provide block scope without hoisting headaches. Can some explain why in the code below i in the function resolves to the last value from the loop (just like with var) instead of the value from the current iteration?

use strict;

var things = {};

for (let i = 0; i < 3; i++) {

    things[fun + i] = function() {

        console.log(i);

    };

}



things[fun0](); // prints 3

things[fun1](); // prints 3

things[fun2](); // prints 3

According to MDN using let in the for loop like that should bind the variable in the scope of the loop's body. Things work as I'd expect them when I use a temporary variable inside the block. Why is that necessary?

use strict;

var things = {};

for (let i = 0; i < 3; i++) {

    let index = i;

    things[fun + i] = function() {

        console.log(index);

    };

}



things[fun0](); // prints 0

things[fun1](); // prints 1

things[fun2](); // prints 2

I tested the script with Traceur and node --harmony.