一、要求

This challenge is a little bit more complex
Write a function that takes a number (a) as argument
If a is prime, return a
If not, return the next higher prime number

二、解

function myFunction( a ) {
    
  function isPrime(num) {
    
    for (let i = 2; i <= Math.sqrt(num); i++) {
    
      if (num % i === 0) return false;
    }
    return num > 1;
  }
 let n = a;
 while (!isPrime(n)) n++;
return n
}