function formValidator() {
    // Make quick references to our fields
    var name = document.getElementById('cname');
    var email = document.getElementById('cemail');
    var captcha = document.getElementById('captcha');

    // Check each input in the order that it appears in the form!
    if (notEmpty(name, "請輸入姓名")) {
        if (emailValidator(email, "請輸入正確email")) {
            if (notEmpty(captcha, "請輸入驗證碼")) {
                return true;
            }
        }
    }
    return false;
}

function notEmpty(elem, helperMsg) {
    if (elem.value.length == 0) {
        alert(helperMsg);
        elem.focus(); // set the focus to this input
        return false;
    }
    return true;
}

function isNumeric(elem, helperMsg) {
    var numericExpression = /^[0-9]+$/;
    if (elem.value.match(numericExpression)) {
        return true;
    } else {
        alert(helperMsg);
        elem.focus();
        return false;
    }
}

function isAlphabet(elem, helperMsg) {
    var alphaExp = /^[a-zA-Z]+$/;
    if (elem.value.match(alphaExp)) {
        return true;
    } else {
        alert(helperMsg);
        elem.focus();
        return false;
    }
}

function isAlphanumeric(elem, helperMsg) {
    var alphaExp = /^[0-9a-zA-Z]+$/;
    if (elem.value.match(alphaExp)) {
        return true;
    } else {
        alert(helperMsg);
        elem.focus();
        return false;
    }
}

function lengthRestriction(elem, min, max) {
    var uInput = elem.value;
    if (uInput.length >= min && uInput.length <= max) {
        return true;
    } else {
        alert("Please enter between " + min + " and " + max + " characters");
        elem.focus();
        return false;
    }
}

function madeSelection(elem, helperMsg) {
    if (elem.value == "Please Choose") {
        alert(helperMsg);
        elem.focus();
        return false;
    } else {
        return true;
    }
}

function emailValidator(elem, helperMsg) {
    var emailExp = /^[\w\-\.\+]+\@[a-zA-Z0-9\.\-]+\.[a-zA-z0-9]{2,4}$/;
    if (elem.value.match(emailExp)) {
        return true;
    } else {
        alert(helperMsg);
        elem.focus();
        return false;
    }
}