ajax send data to php file : send `$username` php with ` data:  new FormData(this),` to add.php like `data:  new FormData(this),$username` how can i do it with ajax code


    <script type="text/javascript">
    $(document).ready(function (e) {
	$("#uploadFormuserimg").on('submit',(function(e) {
		e.preventDefault();
		$.ajax({
        	url: "add.php",
			type: "POST",
			data:  new FormData(this),
			contentType: false,
    	    cache: false,
			processData:false,
			success: function(data)
		    {
			$("#user_img_a").html(data);
		    },
		  	error: function() 
	    	{ alert("error");
	    	} 	        
	      });
	      }));
        });
        </script>