javascript 邮箱验证 和让控件获得焦点

if(document.all.Text5.value=="")
          {
              alert("“电子邮箱”不能为空");
              document.all.Text5.focus();
              return false;
          }
          else
          {
              if(isEmail(document.all.Text5.value)==false)
              {
                  alert("电子邮箱格式不正确不能为空");
                  document.all.Text5.focus();
                  document.all.Text5.select();
                  return false;
              }
          }

           function isEmail(s)
      {
          s = s.replace(/＠/ig, "@");
          if (s.search(/^\w+((-\w+)|(\.\w+))*\@[A-Za-z0-9]+((\.|-)[A-Za-z0-9]+)*\.[A-Za-z0-9]+$/) != -1)

          return true;
          else return false;
      }