JSFiddle - React, Tailwind, and code Playground

HTML

<form name="form1" id="form1">
    <input type="hidden" id="productid" name="productid" />
    <input type="hidden" id="command" name="command" />
    </form>

JavaScript

function addtocart(pid){
        $("#productid").val(pid);
        $("#command").val('add');
        ajaxSubmit();
}
function ajaxSubmit() {
    $.ajax({
      type: "POST",
      url: "mypage.php",
        data: {"productid": $("#productid").val(), "command": $("#command").val()},
        success: function(returnedData) {
             alert(returnedData);   
        }
    });   
}
addtocart(12);