A Common-Sense Guide to Data Structures and Algorithms in JavaScript, Volume 1

Recurse Instead of Loop

Let’s say you work at NASA and need to program a countdown function for launching spacecraft. The particular function that you’re asked to write should accept a number—such as 10—and display the numbers from 10 down to 0.

Take a moment and implement this function yourself. When you’re done, read on.

Odds are that you wrote a simple loop, along the lines of this implementation:

function countdown(number) {
  while (number >= 0) {
    console.log(number);
    number -= 1;
  }
}

Nothing is wrong with this implementation, but it may have never occurred to you that you don’t have to use a loop.

How?

Let’s try recursion instead. Here’s a first attempt at using recursion to implement our countdown function:

function countdown(number) ...