ES6: for loop issue solved

scoping.js

// BAD
for(var i = 0; i < 10; i++) {
    console.log(i); // 0 1 2 3 4 5 6 7 8 9
    setTimeout(function() {
      console.log('The number is ' + i);
    },1000);
  } // -> 'The number is 10' printed 10 times

// GOOD
for(let i = 0; i < 10; i++) {
    console.log(i); // 0 1 2 3 4 5 6 7 8 9
    setTimeout(function() {
      console.log('The number is ' + i);
    },1000);
  }// you get each number printed (from 0 to 9)