If you missed the introductory post, it's here. For a list of previously solved katas, please refer to the bottom of this page.

If this is your first time seeing my post, please note - these katas are probably randomly assigned per user so please don't go into Codewars thinking we will have exactly the same user experience, I am just posting these in the order that I got them.

Kata #19

DESCRIPTION:

You might know some pretty large perfect squares. But what about the NEXT one?

Complete the findNextSquare method that finds the next integral perfect square after the one passed as a parameter. Recall that an integral perfect square is an integer n such that sqrt(n) is also an integer.

If the parameter is itself not a perfect square then -1 should be returned. You may assume the parameter is non-negative.

Examples:(Input --> Output)

121 --> 144
625 --> 676
114 --> -1 since 114 is not a perfect square

Starting code:

function findNextSquare(sq) {
  // Return the next square if sq is a perfect square, -1 otherwise
  return -1;
}

My attempt that worked:

function findNextSquare(sq) {
  let sqrtCheck = (sq**.5)
  if (Number.isInteger(sqrtCheck) == true){
    return ((sq**.5)+1)**2
  }else{
    return -1
  }
}

Had to research and learned about the .isInteger() method. Wanted to shorten my solution to a one-liner so it turned into this:

const findNextSquare = sq => Number.isInteger(sq**.5) ? ((sq**.5)+1)**2 : -1

Moving on to best practices, we see rank #1 with the Math object combined with the .sqrt() method and using the modulus operator:

function findNextSquare(sq) {
  return Math.sqrt(sq)%1? -1 : Math.pow(Math.sqrt(sq)+1,2);
}

Rank #2:

function findNextSquare(sq) {
  var number = Math.sqrt(sq);
  if(Math.round(number) === number) {
    return Math.pow(++number, 2)
  }
  return -1;
}

Rank #3 is quite similar to rank #1 but with an additional variable declaration:

function findNextSquare(sq) {
  var root = Math.sqrt(sq);
  return root % 1 === 0 ? Math.pow(root + 1, 2) : -1;
}

Rank #4 is where my initial approach falls under by using the Number.isInteger() method:

function findNextSquare(sq) {
  // Return the next square if sq if a perfect square, -1 otherwise
  var root = Math.sqrt(sq);
  if (Number.isInteger(root)) {
    return Math.pow(root + 1, 2);
  } else {
    return -1;
  }
}

Notable mention at rank #5 with 131 'Clever' votes at the time of writing:

function findNextSquare(sq) {
    let r = Math.sqrt(sq)
    return r % 1 ? -1 : ++r * r
}

That's it for Kata #19, stay tuned for more katas to be solved!

Link to Kata #1: Square(n) Sum

Link to Kata #2: Convert a Number to a String

Link to Kata #3: DNA to RNA Conversion

Link to Kata #4: Remove First and Last Character

Link to Kata #5: MakeUpperCase

Link to Kata #6: Total amount of points

Link to Kata #7: A Needle in the Haystack

Link to Kata #8: Sum of positive

Link to Kata #9: Basic Mathematical Operations

Link to Kata #10: Beginner - Reduce but Grow

Link to Kata #11: Square Every Digit

Link to Kata #12: Friend or Foe?

Link to Kata #13: Grasshopper - Summation

Link to Kata #14: Get the Middle Character

Link to Kata #15: Descending Order

Link to Kata #16: String ends with?

Link to Kata #17: Sum of two lowest positive integers

Link to Kata #18: Sum of odd numbers