function validateFormOnSubmit(theForm) {
var reason = "";

  reason += validateUsername(theForm.loginid);
  reason += validatePassword(theForm.loginpw);
  reason += validateEmail(theForm.email);
//  reason += validateEmpty(theForm.from);
      
  if (reason != "") {
    alert("以下部份項目必須輸入:\n" + reason);
    return false;
  }

  return true;
}

function validateEmpty(fld) {
    var error = "";
  
    if (fld.value.length == 0) {
        fld.style.background = 'Yellow'; 
        error = "The required field has not been filled in.\n"
    } else {
        fld.style.background = 'White';
    }
    return error;   
}

function validateUsername(fld) {
    var error = "";
    var illegalChars = /\W/; // allow letters, numbers, and underscores
 
    if (fld.value == "") {
        fld.style.background = 'Yellow'; 
        error = "請輸入登入名稱\n";
    } else if ((fld.value.length < 4) || (fld.value.length > 15)) {
        fld.style.background = 'Yellow'; 
        error = "登入名稱最少輸入4個字元\n";
    } else if (illegalChars.test(fld.value)) {
        fld.style.background = 'Yellow'; 
        error = "登入名稱不可包含特殊字元\n";
    } else {
        fld.style.background = 'White';
    } 
    return error;
}

function validatePassword(fld) {
    var error = "";
    var illegalChars = /[\W_]/; // allow only letters and numbers 
 
    if (fld.value == "") {
        fld.style.background = 'Yellow';
        error = "請輸入登入密碼\n";
    } else if (fld.value.length < 4) {
        error = "登入密碼最少輸入4個字元\n";
        fld.style.background = 'Yellow';
    } else if (illegalChars.test(fld.value)) {
        error = "登入密碼不可包含特殊字元\n";
        fld.style.background = 'Yellow';
    } else {
        fld.style.background = 'White';
    }
   return error;
}  

function trim(s)
{
  return s.replace(/^\s+|\s+$/, '');
} 

function validateEmail(fld) {
    var error="";
    var tfld = trim(fld.value);                        // value of field with whitespace trimmed off
    var emailFilter = /^[^@]+@[^@.]+\.[^@]*\w\w$/ ;
    var illegalChars= /[\(\)\<\>\,\;\:\\\"\[\]]/ ;
    
    if (fld.value == "") {
        fld.style.background = 'Yellow';
        error = "請輸入電郵地址\n";
    } else if (!emailFilter.test(tfld)) {              //test email for illegal characters
        fld.style.background = 'Yellow';
        error = "電郵地址不正確\n";
    } else if (fld.value.match(illegalChars)) {
        fld.style.background = 'Yellow';
        error = "電郵地址不可包含特殊字元\n";
    } else {
        fld.style.background = 'White';
    }
    return error;
}
function validatePhone(fld) {
    var error = "";
    var stripped = fld.value.replace(/[\(\)\.\-\ ]/g, '');     

   if (fld.value == "") {
        error = "You didn't enter a phone number.\n";
        fld.style.background = 'Yellow';
    } else if (isNaN(parseInt(stripped))) {
        error = "The phone number contains illegal characters.\n";
        fld.style.background = 'Yellow';
    } else if (!(stripped.length == 10)) {
        error = "The phone number is the wrong length. Make sure you included an area code.\n";
        fld.style.background = 'Yellow';
    } 
    return error;
}