Using let with for Loops

The let keyword is especially useful in for loops. Using var to define the counter in a for loop can lead to confusing and unexpected outcomes. For example, consider the following code:

for ( var i = 0; i < 10; i++ ) {
  console.log(i); // logs the numbers 0 to 9
}
console.log(i); // 10

The for loop logs the value of i to the console ten times. When the loop is ...