check prime

by Paco86

JavaScript

function isPrime(val){
	if(val < 2){
  	return false;
  }else if(primeArr[val] !== undefined){
  	return primeArr[val];
  }
  
	let sqrt = parseInt(Math.sqrt(val));
  for(let i = 2; i < sqrt; i++){
  	if(val % i === 0){
    	primeArr[val] = false;
			return false;    
    }
  }
  primeArr[val] = true;
  return true;
}

console.log(isPrime(12));
console.log(isPrime(12));