freeCodeCamp Challenge Guide: Reverse an Integer

Reverse An Integer


Problem Explanation

We should create a function that takes an integer and returns the integer’s order of numbers in reverse. We should also make sure that negative integers remain negative.

Relevant Links


Hints

Hint 1

Although we need to return a number, we can convert a number into a string, perform some operations, and then convert back into a number and return the value…

Hint 2

With the help of Math.sign, we can ensure negative numbers remain negative by multiplying the function’s return value with the sign of the original number.


Solutions

Solution 1 (Click to Show/Hide)
js
function reverseInt(n) {
  const rev = n
  .toString()
  .split('')
  .reverse()
  .join('')
  return parseInt(rev) * Math.sign(n)
}

Code Explanation

  • Create a new variable and set it to n (our original integer)
  • Chain .toString() to n in order to first convert the number into a string.
  • Split the string with the method .split("") into an array of substrings to access each unique integer.
  • We can now reverse the array of numbers with .reverse().
  • Switch the array back into a string using .join(’’) method.
  • Now return the reversed string and convert it back to an integer with parseInt().
  • Finally, multiply the resulting number by the sign of the function’s original number using Math.sign() to make sure negative numbers are returned in their negative form.

Relevant Links