<script>
   var str="this is a test"
   with (document)
   {
       write("原是字符串："+str);
       write("<br>");
       write("small方法作用后:"+str.small());
       write("<br>");
       write("small方法的返回值"+"<input type='text' size=30 value='"+str.small()+"'>");
   }
</script>