regex: 替换不可见字符(空格等)

<script type="text/javascript">
     function f(str,direct){
         var s = str;
         if(direct=="left"){
             s = str.replace(/^\s*/,"");
         }else if(direct=="right"){
             s = str.replace(/\s*$/,"");
         }else{
             s = str.replace(/\s*/g,"");
         }
         return s;
     }
     
     alert("|"+f("     a      b     c       ", "right")+"|");
      
  </script>