Codewars Tutorial — 7kyu: You’re a square!

My solution and explanation for codewars.com katas

Train: You're a square! | Codewars

Instructions:

A square of squares

You like building blocks. You especially like building blocks that are squares. And what you even like more, is to arrange them into a square of square building blocks!

However, sometimes, you can’t arrange them into a square. Instead, you end up with an ordinary rectangle! Those blasted things! If you just had a way to know, whether you’re currently working in vain… Wait! That’s it! You just have to check if your number of building blocks is a perfect square.

Task

Given an integral number, determine if it’s a square number:

In mathematics, a square number or perfect square is an integer that is the square of an integer; in other words, it is the product of some integer with itself.

The tests will always use some integral number, so don’t worry about that in dynamic typed languages.

Examples

isSquare(-1) returns false
isSquare(0) returns true
isSquare(3) returns false
isSquare(4) returns true
isSquare(25) returns true
isSquare(26) returns false

First solution

var isSquare = function(n){
let numchk;
for(let i = 0; i < n+1; i++){
numchk = n/i;
if(i === numchk){
return true;
}
}
if(n<0){
return false
} else if(numchk==1) {
return false
} else {
return true
}
}

Refactoring solution with Explanation

var isSquare = function(n){

• create numchk variable

let numchk;

• loop thru each number to n+1
• ie. if n is 4
• loop 0,1,2,3, and 4 (hence i+1)

for(let i = 0; i < n+1; i++){

• numchk will equal n/i
• divide each i into n
• so 4/4, 4/3, 4/2, 4/1, and 4/0
• and set numchk to that value
• ie. 4/2 = 2 so set numchk to 2

numchk = n/i;

• when looping if i matches numchk return true
• in the example when 4/2 = 2, numchk was 2 and i was 2, so there was a match and the return is true.
• but for the others, 4/3 = 1.33 so numchk is 1.33 and i was 3 there is no match

if(i === numchk){
return true;
} else {

• if i does not equal numchk then set numchk to 1

numchk = 1
}
}

• used a ternary conditional operator
• https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Conditional_Operator
• this say — if n is less than 0 or numchk equals 1 and n is NOT 0 then return false, else return true

return (n<0 || numchk==1 && n!=0) ? false : true
}