Need to combine JavaScript funtions from 2 buttons

Hi,
How can I combine JavaScript functions from 2 buttons?

<input name="Submit" type="submit" onclick="javascript:window.print()" value="Print Details" />

<input type="button" class="button green" onClick="if(checkFields()){location.href='process_payment.php?cartId=<?php echo $cookie;?>'}" value="Process Order" >

Select allOpen in new window

I would like my print button to have an alert "please note that the order details have not been processed yet, do you want to process this order now?"

and if they click ok then execute  "if(checkFields()){location.href='process_payment.php?cartId=<?php echo $cookie;?>'}"



I was also wondering if it is better to move location.href='process_payment.php?cartId=<?php echo $cookie;?> to the checkFields function and can I add an animated gif to this function?

<script language="JavaScript" type="text/javascript" >
   //<!--
  var clickcount = 0;

   function checkFields(){
     if (clickcount == 0) {
       //count clicks 
       clickcount ++;
       return true;
     }
     else {
       alert("Transaction already in progress.. Please wait...");
       return false;
     }
   }
   //-->

</script>

Select allOpen in new window