Sending multiple data parameters with jQuery AJAX

I am sending an ajax request to a php file as shown here:

function checkDB(code, userid)
{

  $.ajax({
  type: "POST",
  url: "<?php bloginfo('template_url'); ?>/profile/check_code.php",
  data: 'code='+code+'userid='+userid,
  datatype: "html",
  success: function(result){

	   if(result == 0)
	   	{
			$('#success').html( code + ' has been redeemed!');
			// alert('success');//testing purposes
	   	}
	   	else if(result == 2)
	   	{
			$('#err').html(  code + ' already exists and has already been redeemed....');
			//alert('fail');//testing purposes
	   	}else if(result == 1){
			$('#err').html(  code + ' redeem code doesnt exist');	   
		}
	   
		alert(result);	    
	  }
  })
	 
}

This is sent calling the function on submit, like so:

<form method="post" class="sc_ajaxxx" id="sc_add_voucherx" name="sc_ajax"  
     onsubmit="checkDB(document.sc_ajax.sc_voucher_code.value, <?php echo $user_id ?>); return false;">
</form>

The problem is that the user id php variable is not getting sent to the check_code.php page by ajax. or at least I cant seem to echo the id back to the page.

Is this the correct way of passing multiple values to a server-side page? Without the userid passing over, it works fine just passing over the code.

Thanks guys :)

Here is how POST data should be formatted:

key1=value1&key2=value2&key3=value3

In your case (note the & as a separator):

'code=' + code + '&userid=' + userid

But jQuery does that for you if you specify your data as an object:

data: { code: code, userid: userid }

you should set your data like so :

data: 'code='+code+'&userid='+userid

you can try this :

data: 'code='+code+'&userid='+userid,

instead of

data: 'code='+code+'userid='+userid,

usually sending your data like this helps:

data: { code: code, userid: userid }

the most important thing to not forget is to verify if the name of the variables you are sending are the same in the server side

The answer from Linus Gustav Larsson Thiel refers, I used the following &.ajax() that triggers when a button is clicked and it works great. I could pass day, month and year parameters.

$('#convertbtn').on('click',function(){
ageddajax = $("#agedd").val();
agedmmajax = $("#agemm").val();
ageyyyyajax = $("#ageyyyy").val();
	if(ageddajax > 0 && agemmajax > 0 && ageyyyyajax >0){
	$.ajax({
        type:'POST',
        url:'ajaxDataAge.php',
        data:'agedd_id='+ageddajax +'&agemm_id='+agemmajax +'&ageyyyy_id='+ageyyyyajax,
        	success:function(html){
            $('#cydivage').html(html);
        	}
		});
	} 	
});

Try this code... it is working for me ...

<script type='text/javascript'>
$(document).ready(function(){
  $(".star").click(function(){
   var rate_value1= $(this).index(".star")+1;
    $.ajax({
	type: "POST",
	dataType: "json",
	url:  "<?php echo(rootpath()) ?>/vote.php",
				
data: { product_id: '<?php echo($product_id_to_permalink) ?>' , rate_value: rate_value1 }
				
		});
	  });
	});
</script>		

 Try this code... 
    <script>
     function quote_ajax_table(){
       var doc_name = '<?php echo $test; ?>';
       var doc_no = '<?php echo $doc_no; ?>';

$.get('quote_ajax_table.php?doc_no='+doc_no+'&doc_name='+doc_name,function(data) {
   $('.dyna').html(data);
 });
}
</script>

//in html code 
  <div class="dyna"></div>