Why when I use ajax request, there comes out more prefix?

I have a config.js:

function get_config() {


  var domain = "www.example.net";
  var base_url = domain + '/includes/api.php';

  return {
    domain: domain, // domain
    base_url: base_url,
  }
}

When I use it:

<script>

        function login() {

          console.log("log in");

          var configs = get_config()
          var base_url = configs.base_url;

          console.log(base_url);  // there output: `www.example.net/includes/api.php`

          var opt = {
            action: "ValidateLogin",
            email: $("#login_email").text(),
            password2: $("#login_password").text(),
            responsetype: 'json'
          }

          $.ajax({
            type: "post",
            url: base_url,
            dataType : "json",
            //contentType : "application/json",
            data: opt,  // JSON.stringify(opt)
            success: function (data) {
              console.log(data);
            },
            error: function (jqXHR, textStatus, errorThrown) {
              console.log(jqXHR, textStatus, errorThrown);
            }
          });

        }

      </script>

You see I use the base_url: but there get error when I run the login() function:

Request URL: http://localhost:63342/template/www.example.net/includes/api.php
Request Method: POST
Status Code: 404 Not Found
Remote Address: 127.0.0.1:63342
Referrer Policy: no-referrer-when-downgrade

You see there added the additional prefix http://localhost:63342/template/. why?

I run the project with WebStorm.