JQuery/Javascript and the use of && operators

I'm trying to get a simple conditional statement to work, and running into problems. The failing code:

    $(document).ready(function(){
     var wwidth = $(window).width();
 
     if (wwidth < 321) {
         alert("I am 320 pixels wide, or less");
         window.scrollTo(0,0);
     } else if (wwidth > 321) && (wwidth < 481) {
         alert("I am between 320 and 480 pixels wide")
     }
 });
 

If I remove the else if part of the code, I get the alert. If I try to use && or || operators it will fail. I've Googled, I can't find a reason why it's not working. I've also tried:

((wwidth > 321 && wwidth < 481))
 

along with other ways, just in case it's some odd syntax thing.

Any help would be greatly appreciated. Thanks :)

---