Always perfect.js

/*
Description:
While surfing in web I found interesting math problem called "Always perfect". That means if you add 1 to the product of four consecutive numbers the answer is ALWAYS a perfect square. For example we have: 1,2,3,4 and the product will be 1X2X3X4=24. If we add 1 to the product that would become 25, since the result number is a perfect square the square root of 25 would be 5.

So now lets write a function which takes numbers separated by commas in string format and returns the number which is a perfect square and the square root of that number.

If string contains other characters than number or it has more or less than 4 numbers separated by comma function returns "incorrect input".

If string contains 4 numbers but not consecutive it returns "not consecutive".
*/
function checkRoot(string){
  const arr=string.split(',').map(v=>v*1);
  if (arr.some(v=>isNaN(v)||v===0)||arr.length!==4) return 'incorrect input';
  const sum=arr.reduce((a,b)=>a*b,1);
  if (arr.map((v,i,arr)=>arr[i]+1===arr[i+1]).filter(v=>v===false).length>1) return 'not consecutive'
  return `${sum+1}, ${Math.sqrt(sum+1)}`
}