function checknull(theField,theAlert) {
  if (theField.value=="" || theField.value=="undefined"){
    window.alert(theAlert); 
    theField.focus();
  return false;
  } else {
    tmp = theField.value;
    while (tmp.charAt(0) == " ")
      tmp=tmp.substring(1);
    if (tmp == "") {
      window.alert(theAlert);
      theField.focus();
      return false;
    }
  }
  return true;
}

function load(Object) { 
  if (Object.selectedIndex > 0) 
    location = Object.options[Object.selectedIndex].value;
}

function checkUseridValid(theField,theAlert) { 
  var patrn=/^([a-zA-Z0-9]){4,20}$/;
  if (!patrn.exec(theField.value)) {
    alert(theAlert);
    theField.focus();
    return false;
  } else {
    return true;
  }
} 

function CheckUserID() {
  var user_id = document.create_account.user_id.value;
  if (!checknull(document.create_account.user_id,"    用户名不能为空")) {
    return false;
  }
  if (document.create_account.user_id.value.length < 4 || document.create_account.user_id.value.length > 20) {
    window.alert("用户名的长度须在4到20个字符之间");
   return false;
  }
  if (!checkUseridValid(document.create_account.user_id,"用户名只能由字母或数字组成，并且不能包含空格")) {
    return false;
  }
  return window.showModalDialog("checkuserid.php?user_id="+user_id,"","status:no;resizable:no;dialogHeight:180px;dialogWidth:500px;unadorne:yes");
}

function cfmdel() {
  if (confirm("删除记录可能造成不确定后果，确认删除吗？"))
	return true;
  else
	return false;
}

function cfmcopy() {
  if (confirm("确认将该项目转移到大会网站吗？"))
	return true;
  else
	return false;
}