title: 'Bootsrap 4.0.0 stable' causes 'Uncaught TypeError: Cannot read property 'apply' of undefined.'
body: <p>So far I have been using Bootstrap 4.0.0-beta2 and the plugin jquery-Validate vs. 1.17.0 to validate form data.
  That was ok.</p>
  
  <p>Now I went over to 'Bootstrap 4.0.0 stable' and got the following error:</p>
  
  <pre><code>jquery.validate.min.js:4 Uncaught TypeError: Cannot read property 'apply' of undefined.  Exception occurred when checking element idUserNameProvRegister, check the 'remote' method.
      at Function.a.ajaxPrefilter.a.ajax (jquery.validate.min.js:4)
      at a.validator.remote (jquery.validate.min.js:4)
      at a.validator.check (jquery.validate.min.js:4)
      at a.validator.element (jquery.validate.min.js:4)
      at a.validator.onfocusout (jquery.validate.min.js:4)
      at HTMLInputElement.b (jquery.validate.min.js:4)
      at HTMLFormElement.dispatch (jquery-3.2.1.slim.min.js:3)
      at HTMLFormElement.q.handle (jquery-3.2.1.slim.min.js:3)
      at Object.trigger (jquery-3.2.1.slim.min.js:3)
      at Object.simulate (jquery-3.2.1.slim.min.js:3)
  </code></pre>
  
  <p>The problem seems to arise from this part of code that is needed by the jquery-Validation plugin:</p>
  
  <pre><code>  $("#idFormProvRegister").validate({
  
          rules:{
            UserNameProvRegister: {
                  required:       true,
                  length_username: true,
                  alphanumeric:   true,
  
                  remote: {   
                      url: "ajax/IstUserNameVergeben.php",
                      type: "post",
                      data: {
                          UserNameProvRegister: function(){
                              return $("#idUserNameProvRegister").val();
                          }
                      }              
                  }
            },
    .....
  </code></pre>
  
  <p>I have made no changes to my own code except for these cdns (required for new Bootstrap version):</p>
  
  <pre><code>&lt;link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous"&gt;
  
     &lt;script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"&gt;&lt;/script&gt;
     &lt;script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js" integrity="sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q" crossorigin="anonymous"&gt;&lt;/script&gt;
     &lt;script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js" integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl" crossorigin="anonymous"&gt;&lt;/script&gt;
  </code></pre>
  
  <p>In both cases ('BS 4.0.0 beta2' as well as 'BS 4.0.0 stable') I used the same jquery version.
  Does anybody know how to solve that issue?</p>
  
  <p>Henry</p>