how can add javascript class data into php varible : 

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-js -->

    function net_total(){
    		var net_total = 0;
    		$('.qty').each(function(){
    			var row = $(this).parent().parent();
    			var price  = row.find('.price').val();
    			var total = price * $(this).val()-0;
    			row.find('.total').val(total);
    		})
    		$('.total').each(function(){
    			net_total += ($(this).val()-0);
    		})
    		$('.net_total').html("Total : $ " +net_total);
    	}

<!-- language: lang-html -->

    <div class="col-md-4"> 
    								<b class="net_total" style="font-size:20px;"> </b>
    					</div>

<!-- end snippet -->

We want net_total class data add in to another php varible like,how can insert dnet_total class data in to data base by php 