我使用javascript提交表单但我无法在php页面中获取值

I am using this code to submit my form

    $('.login-form input').keypress(function (e) {
        if (e.which == 13) {
            if ($('.login-form').validate().form()) {
            //$( "#login-form input" ).submit();
               // window.location.href = "check.php";
     $.post("check.php", $("#login-form input").serialize(),               function(data) {
     window.location.href = "check.php";
      });
            }
            return false;
        }
    });

I am not able to get values in check.php. kindly help me. I know its a basic thing but I am not able to do this. Thanks in advance

Here is my php code

       <?php
       session_start();
       include_once("Includes/db_connection.php");
       include_once("participant/welcome.php");
       include_once("admin/admin_login.php");
       include_once("staff/staff_login.php");
       include_once("lecturer/lecturer_login.php");
       include("Includes/location.php");
       //include("Includes/lecturer_data_dropdown.php");

       $username=$_POST["username"];
       $password=$_POST["password"];
       echo $username;
       if($_POST["user_type"]=="participant")
       {
       participant($password); 
       }
       elseif($_POST["user_type"]=="admin")
       {
       admin($username, $password); 
       }
       elseif($_POST["user_type"]=="staff")
       {
       staff($username, $password); 
       }
       elseif($_POST["user_type"]=="lecturer")
       {
       lecturer($username, $password);
       }

       ?>

Here i just need usertype, username and password to make login decisions

I notice you're referencing $('.login-form') in one section of your code and $('#login-form') in another. If your form is in fact using a class instead of an ID, the .serialize() method will return an empty array. Update it to $('.login-form input') (note the period instead of the hash).

More info on jQuery selectors: https://api.jquery.com/category/selectors/

Try this i've tried and its working just fine:

var var_username=$("Id of input box for username").val();
var var_password= $("Id of input box for password").val();

$.post(URL,
  {
    username: var_username,
    password: var_password
  },
  success:function(data)
  {
      //your message here..
  }
);