var ReqField = new RequiredField()
var ASPID = 'ctl00_ContentPlaceHolder1_';

ReqField.Add(ASPID + 'tbx_FirstName', 'text', 'Enter Your First Name.');
ReqField.Add(ASPID + 'tbx_LastName', 'text', 'Enter Your Last Name.');
ReqField.Add(ASPID + 'tbx_EmailID', 'text', 'Enter Your Email ID.');
ReqField.RegEx(ASPID + 'tbx_EmailID', /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/, '', 'Invalid email address');                             
ReqField.Add(ASPID + 'tbx_ContactNoDay', 'text', 'Enter Your Day Contact No.');
ReqField.Add(ASPID + 'tbx_ContactNoEve', 'text', 'Enter Your Evening Contact No.');
ReqField.Add(ASPID + 'tbx_Message', 'text', 'Enter Message.');        

function CheckInputs() {
    try {
        
        var Msg = ReqField.Check();
        if (Msg[0]) {
            return true;
        }
        else {
            alert(Msg[1])
            return false;
        }
    }
    catch (e) {
        alert(e);
    }    
}