function islegality(checkstrpass){
var checkokpass="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
for (i=0; i<checkstrpass.length; i++)
  {
       ch=checkstrpass.charAt(i);
       for (j=0;j<checkokpass.length; j++){
        if (ch==checkokpass.charAt(j))
        break;
        }

      if (j==checkokpass.length){
	  return false; //函有特别字符时返回false
      break;
        }
  }


   return true;
}

function trim(inputStr) {
	var result = inputStr;
	while (result.substring(0,1) == " ") {
		result = result.substring(1,result.length)
	}
	
	while (result.substring(result.length-1, result.length) == " ") {
		result = result.substring(0, result.length-1)
	}
		
	return result;
}

function checkLogon(objForm){
    if (trim(objForm.mbrName.value)=="" || trim(objForm.password.value)=="") 
    {
        alert ("必须提供用户名和密码，请确认！")
		objForm.mbrName.value="";
        objForm.password.value="";
		objForm.mbrName.focus();
        return false;
    }
	 if (!islegality(objForm.mbrName.value))
     {
      alert('你输入的用户名含有无效字符!');
		objForm.mbrName.value="";
        objForm.mbrName.focus();
	  return false;
      }	
    return true;
}