Question

How do I pass a value from JavaScript code to a servlet page?

Answer 1

As per my understanding , Create a hidden input field , set the value and submit to the action and get the hidden field value from servlet.

This shows a kick-off example , you can modify it according to your needs :
HTML Form :

<form name="myForm">  
<input type=hidden name="hiddenValue"/>  
<input type="submit" value="Submit" name="buttonSubmit" onclick="customSubmit(10)"/>  
</form>  

Script :

<script>  
 function customSubmit(someValue){  
 document.form1.hiddenValue.value = someValue;   
 document.form1.submit();  
 }  
</script>  

You would user Request.getParameter to get this value from servlet .