How to use jQuery AJAX in ember v3.2.5?

I tried writing code that gives the alert message inside the function but the success or error block seems doesn’t work.

How can I call the function properly? I'm using the latest Ember version (3.2.5). Here is my AJAX code in the app/controller

import Controller from '@ember/controller';
import $ from 'jquery';
export default Controller.extend({
  actions: {
    validateUser: function() {
      let res = this;
      var userName = this.get('username');
      var userPassword = this.get('password');

      $.ajax({
        type: "POST",
        url: "InsertServlet",
        data: {
          userId: userName,
          password: userPassword
        },
        success: function(data) {
          if (data == 1) {
            alert('valid user');
          } else {
            alert("Invalid User");
          }
        },
        error: function(xhr, status, error) {
          alert(xhr.responseText);
        }
      });
    },
  }
});