jQuery Ajax乘法

Question

I need your help please! I want to multiply the quantity with the single price and put it in id called total using Ajax( I don't know Ajax well)

$(function () {
    "use strict";
    $('.qty').on('keyup', function () {
        var singl_price = $(".single_price").val(),
            qty = $(".qty").val(),
            total_price = qty * singl_price;
            $("#total").text(total_price);

        $.ajax({
            url: 'cart.php',
            type: 'POST',
            data: '',
            success: function (data) {
                if (data === "ok") {                    
                }
            },
            error: function (e) {
            }
        });    
    });   
});

<form action="cart.php" method="post" >
  <input type="text" name="qty" class="qty" value="<?php echo $_POST['qty']; ?>" />
</form>

<div class="single_price"> 20 </div>

<div id="total"> </div>

</div>

Answer 1

try:

$('.qty').on('keyup', function () {
        $.ajax({
            url: 'cart.php',
            type: 'POST',
            data: {total_price:total_price},
            success: function (data) {
                   var total = 0;
                   $('.qty').each(function(i,v){
                   var singl_price = $(v).next(".single_price").text();
                   var qty = $(v).val().length > 0 ?$(v).val():0;

                  total +=  parseInt(qty) * parseInt(singl_price);
                  });
                  $('#total').text(total);

                if (data === "ok") {                    
                }
            },
            error: function (e) {
            }
        });    
    });   

html:

<form action="cart.php" method="post" >
      <input type="text" name="qty" class="qty" value="<?php echo $_POST['qty']; ?>" />
    <div class="single_price"> 20 </div>
    </form>



<div id="total">0</div>

https://jsfiddle.net/o7hb7s6g/2/

Note:use parseFloat instead of parseInt if you have price with like 3.99