Integer's divisors 关于整数的约数

Create a function named divisors/Divisors that takes an integer and returns an array with all of the integer‘s divisors(except for 1 and the number itself). If the number is prime return the string ‘(integer) is prime‘ (null in C#) (use Either String a in Haskell and Result<Vec<u32>, String> in Rust).

Example:

divisors(12); // should return [2,3,4,6]
divisors(25); // should return [5]
divisors(13); // should return "13 is prime"

方法一

 1 function divisors(integer) {
 2   var arr = [];
 3   for(var i = 2; i < integer; i++){
 4      if(integer % i ===0){
 5      arr.push(i);}
 6    }
 7   if(arr.length ===0){
 8   return integer+‘ is prime‘;
 9   }else{
10   return arr;}
11 };

上面方法不够完美，for循环里面 i <integer ，有重复，可以用如下方法，更简洁方法二

1 function divisors(integer) {
2   var arr = [];
3   for (var i = 2; i <= Math.floor(integer / 2); ++i)
4   if (integer % i === 0) arr.push(i);
5   return arr.length ? arr : integer + ‘ is prime‘;
6 };

Integer's divisors 关于整数的约数