Reverse A Positive Integer: a visual code tutorial

There are some new tools to generate cool demos of short code snippets, one of these is wave snippets.

I put together a small demo of a very basic problem: write a function to reverse a positive integer.

Meaning take a number like 123 and make it 321. Got it?

I wrote this in typescript, and didn't handle a lot of extra stuff but it works for simple cases. Check it out:

Here is the finished code:

const reversePositiveInt = (toReverse: number):number => {
  let source = toReverse
  let accumulator = 0

  while(true) {
    if(source <= 0) {
      break
    }

    const mod = source % 10
    accumulator += mod
    source = Math.floor(source / 10)
    accumulator *= 10
  }

  return accumulator / 10
}


console.log(reversePositiveInt(12345))
// 54321

The method of doing is this is to shave off the last digit of the input number and put it at the front of a new integer one number at a time.

There is a way to do it faster, but written like this step by step I think it makes it easier to see what is going on.