how to check if the javascript contains atleast 2 alphabets :  i need to check if test contains atleast 2 alphabets like SC then do   something.

        var test='SC129h';
         if(test.containsalphabets atleast 2){
           alert('success');
          }
        else{
      alert('condition not satisfied for alphabets');
        }
 
please let me know how to check the if condition for any alphabets with length 2