Generic Javscript Validation

Here is the JS code
function Validate(objForm) {
    var arrValidated = new Array();
    for (var i = 0; i < objForm.elements.length; i++) {
        var element = objForm.elements[i];
        var elName = element.name;
        if ((!elName) || (elName.length == 0) || (arrValidated[elName]))
            continue;
        arrValidated[elName] = true;
        var validationType = element.getAttribute("validate");
        if ((!validationType) || (validationType.length == 0))
            continue;
        var strMessages = element.getAttribute("msg");
        if (!strMessages)
            strMessages = "";
        var arrMessages = strMessages.split("|");
        var arrValidationTypes = validationType.split("|");
        for (var j = 0; j < arrValidationTypes.length; j++) {
            var curValidationType = arrValidationTypes[j];
            var blnValid = true;
            switch (curValidationType) {
                case "not_empty":
                    blnValid = ValidateNotEmpty(element);
                    break;
                case "integer":
                    blnValid = ValidateInteger(element);
                    break;
                case "number":
                    blnValid = ValidateNumber(element);
                    break;
                case "email":
                    blnValid = ValidateEmail(element);
                    break;
                case "phone":
                    blnValid = ValidatePhone(element);
                    break;
                default:
                    try {
                        blnValid = eval(curValidationType + "(element)");
                    }
                    catch (ex) {
                        blnValid = true;
                    }
            }
            if (blnValid == false) {
                var message = "invalid value for " + element.name;
                if ((j < arrMessages.length) && (arrMessages[j].length > 0))
                    message = arrMessages[j];
                InsertError(element, message);
                if ((typeof element.focus == "function") || (element.focus)) {
                    element.focus();
                }
                return false;
            }
            else
                ClearError(element);
        }
    }
    return true;
}

//Empty Validation

function ValidateNotEmpty(objElement) {
    var strValue = GetElementValue(objElement);
    var blnResult = true;
    if (allTrim(strValue) == "") //check for nothing
    {
        blnResult = false;
    }
    return blnResult;
}


//Integer Validation
function ValidateInteger(objElement) {
    var strString = GetElementValue(objElement);
    var strValidChars = "0123456789";
    var strChar;
    var blnResult = true;
    for (i = 0; i < strString.length && blnResult == true; i++) {
        strChar = strString.charAt(i);
        if (strValidChars.indexOf(strChar) == -1) {
            blnResult = false;
        }
    }
    return blnResult;
}
//Number Validation
function ValidateNumber(objElement)
// check for valid numeric strings
{
    var strString = GetElementValue(objElement);
    var strValidChars = ".0123456789"; //decimal ok
    var strChar;
    var blnResult = true;
    for (i = 0; i < strString.length && blnResult == true; i++) {
        strChar = strString.charAt(i);
        if (strValidChars.indexOf(strChar) == -1) {
            blnResult = false;
        }
    }
    return blnResult;
}



//Email Validation
function ValidateEmail(objElement) {
    // Will check for @, period after @ and text in between
    var strValue = GetElementValue(objElement);
    var in_space = strValue.indexOf(" ");
    if (in_space != -1)
    { return false; }
    var len = strValue.length;
    var alpha = strValue.indexOf("@");
    var last_alpha = strValue.lastIndexOf("@");
    if (alpha != last_alpha)
    { return false; }
    // No @, in first position, or name too short
    if (alpha == -1 || alpha == 0 || len < 6)
    { return false; }
    var last_p = strValue.lastIndexOf(".");
    // Be sure period at least two spaces after @, but not last char.
    if (last_p - alpha < 2 || last_p == (len - 1))
    { return false; }
}


//Valid PhoneNumber

function ValidatePhone(objElement) {
    // non-digit characters which are allowed in phone numbers
    var phoneNumberDelimiters = "()- ";
    // characters which are allowed in international phone numbers
    // (a leading + is OK)
    var validWorldPhoneChars = phoneNumberDelimiters + "+";
    // Minimum no of digits in an international phone no.
    var minDigitsInIPhoneNumber = 10;
    var strValue = GetElementValue(objElement);
    s = stripCharsInBag(strValue, validWorldPhoneChars);
    return (ValidateInteger(s) && s.length >= minDigitsInIPhoneNumber);
}

function GetElementValue(objElement) {
    var result = "";
    switch (objElement.type) {
        case "text":
        case "hidden":
        case "textarea":
        case "password":
            result = objElement.value;
            break;
        case "select-one":
        case "select":
            if (objElement.selectedIndex >= 0)
                result = objElement.options[objElement.selectedIndex].value;
            break;
        case "radio":
        case "checkbox":
            for (var i = 0; i < objElement.form.elements.length; i++) {
                if (objElement.form.elements[i].name == objElement.name) {
                    if (objElement.form.elements[i].checked)
                        result += objElement.form.elements[i].value + ",";
                }
            }
            break;
    }
    return result;
}

function InsertError(element, strMessage) {
    if ((element.form.getAttribute("show_alert")) && (element.form.getAttribute("show_alert") != "0")) {
        alert(strMessage);
        return;
    }
    var strSpanID = element.name + "_val_error";
    var objSpan = document.getElementById(strSpanID);
    if (!objSpan) {
        if ((element.type == "radio") || (element.type == "checkbox")) {
            for (var i = 0; i < element.form.elements.length; i++) {
                if (element.form.elements[i].name == element.name) {
                    element = element.form.elements[i];
                }
            }
        }
        objSpan = document.createElement("span");
        objSpan.id = strSpanID;
        objSpan.className = "validation_error";
        var nodeAfter = 0;
        var nodeParent = element.parentNode;
        for (var i = 0; i < nodeParent.childNodes.length; i++) {
            if (nodeParent.childNodes[i] == element) {
                if (i < (nodeParent.childNodes.length - 1))
                    nodeAfter = nodeParent.childNodes[i + 1];
                break;
            }
        }
        if ((!nodeAfter) && (nodeParent.parentNode)) {
            nodeParent = nodeParent.parentNode;
            for (var i = 0; i < nodeParent.childNodes.length; i++) {
                if (nodeParent.childNodes[i] == element.parentNode) {
                    if (i < (nodeParent.childNodes.length - 1))
                        nodeAfter = nodeParent.childNodes[i + 1];
                    break;
                }
            }
        }

        if (nodeAfter)
            nodeParent.insertBefore(objSpan, nodeAfter);
        else
            document.body.appendChild(objSpan);
    }
    objSpan.innerHTML = strMessage;
}

function ClearError(element) {
    var strSpanID = element.name + "_val_error";
    var objSpan = document.getElementById(strSpanID);
    if (objSpan) {
        objSpan.innerHTML = "";
    }
}

function allTrim(cValue) {
    var lDone = false;
    while (lDone == false) {
        if (cValue.length == 0) { return cValue; }
        if (cValue.indexOf(' ') == 0) { cValue = cValue.substring(1); lDone = false; continue; }
        else { lDone = true; }
        if (cValue.lastIndexOf(' ') == cValue.length - 1) { cValue = cValue.substring(0, cValue.length - 1); lDone = false; continue; }
        else { lDone = true; }
    }
    return cValue;
}

function stripCharsInBag(s, bag) {
    var i;
    var returnString = "";
    // Search through string’s characters one by one.
    // If character is not in bag, append to returnString.
    for (i = 0; i < s.length; i++) {
        // Check that current character isn’t whitespace.
        var c = s.charAt(i);
        if (bag.indexOf(c) == -1) returnString += c;
    }
    return returnString;
}

HTML :
<form action="JsValidation.aspx" show_alert="1" onSubmit="return Validate(this);">

First Name <input type="Text" name="FirstName" maxlength="25" validate="not_empty" msg="First Name is Required" /><br/>

Email <input type="text" name="Email" maxlength="25" validate="email" msg="Email is Required" /><br/>

<input type="submit" value="Go">

</form>