The thing is, I already figured it out(just copy/paste some codes from stackoverflow). But the thing that only matters for me is; Whenever I enter cc number and hits "Tab", it automatically validates the expiration. I used onchange attribute for the 2 boxes. Please help me adjust my codes.
What i would like for the outcome is..
-When i enter cc number, and hit "Tab" the onchange attribute for cc textbox[validates it] and not yet validating the Expiration textbox[not yet validate].
I have tried everything but it only makes it not work..hehe.. Im sorry guys, im not really good at constructing javascripts. Thank you.
Javascript
<!-- START: VALIDATION IN CREDIT CARDS -->
<script type="text/javascript">
//START: FOR CREDIT CARD NUMBER
    function validateCard(card_no){
        var Check_MasterCard = /^([51|52|53|54|55]{2})([0-9]{14})$/;
        var Check_Visa = /^([4]{1})([0-9]{12,15})$/;
        if(Check_Visa.test(card_no)){
            document.getElementById('cardSuccess').style.display = "block";
            document.getElementById('cardSuccess_1').style.display = "none";
            document.getElementById('cardError').style.display = "none";
            return true;
        }else if(Check_MasterCard.test(card_no)){
            document.getElementById('cardSuccess_1').style.display = "block";
            document.getElementById('cardSuccess').style.display = "none";
            document.getElementById('cardError').style.display = "none";
            return true;
        }else{
            document.getElementById('cardError').style.display = "block";
            document.getElementById('cardSuccess_1').style.display = "none";
            document.getElementById('cardSuccess').style.display = "none";
            return false;
        }
    }   
//END: FOR CREDIT CARD NUMBER
    function validateForm(){
        // Set error catcher
        var error = 0;
        // Validate Credit Card
        if(!validateCard(document.getElementById('card_no').value)){
            error++;
        }
        if(error > 0){
           return false;
        }
        //FOR EXPIRY VALIDATION
       var datereg = /^(0[1-9]|1[012])[- /.](19|20)\d\d+$/;
       if (!datereg.test(document.getElementById('credit_card_exp').value)) {
           document.getElementById("expiry_error1").style.display="block";
           document.getElementById("expiry_error").style.display="none";
           return false;
        }
        var currentDate = new Date(); //this returns the current datetime
        //Clear all the other date parts.
        currentDate.setDate(0);
        currentDate.setHours(0);
        currentDate.setMinutes(0);
        currentDate.setSeconds(0);
        currentDate.setMilliseconds(0);   
        var year = parseInt(payment_form.credit_card_exp.value.split('/')[1]);
        var month = parseInt(payment_form.credit_card_exp.value.split('/')[0]);
        var dateToCheck = new Date(year,month,0,0,0,0,0);
        if (dateToCheck.getTime() < currentDate.getTime()){
           //invalid date
           document.getElementById("expiry_error").style.display="block";
           document.getElementById("expiry_error1").style.display="none";
            return false;
        } 
        document.getElementById("expiry_error").style.display="none";
        document.getElementById("expiry_error1").style.display="none";
        return true; 
        //END FOR EXPIRY VALIDATION
    } 
</script>
<!-- END: VALIDATION IN CREDIT CARDS -->
HTML:
<form id='payment_form' name="payment_form" method="post" action="exec_order_process.php" onsubmit="return validateForm();">
Card Number*
<input class="form-control" onchange="return validateForm();" name="card_no" id="card_no" type="text" maxlength="16" required="required" placeholder="Enter Card number" >
<span class="alert alert-danger changeFont" id="cardError" style="display: none;">You must enter a valid Credit Card for VISA and MasterCard Only<span class="glyphicon glyphicon-remove"></span></span>
<span class="alert alert-success changeFont" id="cardSuccess" style="display: none;">This is a VISA card <span class="glyphicon glyphicon-ok"></span></span>
<span class="alert alert-success changeFont" id="cardSuccess_1" style="display: none;">This is a MasterCard <span class="glyphicon glyphicon-ok"></span></span>
Expiration*
<input onchange="return validateForm();" class="form-control" name="credit_card_exp" id="credit_card_exp" type="text" maxlength="7" onchange="validCCForm(this);" required placeholder="MM / YYYY ">
<label class="error" id="expiry_error" style="display: none;">Credit Card Expired</label>
<label class="error" id="expiry_error1" style="display: none;">Enter valid Date Format</label>
<input type="submit" value="Submit">
</form>
 
     
     
    