Count Backwards With a For Loop - antoniojvargas/FreeCodeCamp GitHub Wiki

Count Backwards With a For Loop

A for loop can also count backwards, so long as we can define the right conditions.

In order to count backwards by twos, we'll need to change our initialization, condition, and final-expression.

We'll start at i = 10 and loop while i > 0. We'll decrement i by 2 each loop with i -= 2.

var ourArray = [];
for (var i=10; i > 0; i-=2) {
  ourArray.push(i);
}

ourArray will now contain [10,8,6,4,2].

Let's change our initialization and final-expression so we can count backward by twos by odd numbers. Instructions

Push the odd numbers from 9 through 1 to myArray using a for loop.

// Example
var ourArray = [];

for (var i = 10; i > 0; i -= 2) {
  ourArray.push(i);
}

// Setup
var myArray = [];

// Only change code below this line.
for (var i = 9; i > 0; i -= 2) {
  myArray.push(i);
}