title: $.getJSON call with null parameters to MVC controller action
body: <p>I have a controller with the following action code:</p>
  
  <pre><code>public JsonResult CheckPasswordStrength(string password, string username, string firstname, string lastname)
  {
     ...
     return this.Json(jsonResponse);
  }
  </code></pre>
  
  <p>Then in my javascript on page I call</p>
  
  <pre><code>$.getJSON('http://localhost/site/controller/CheckPasswordStrength', { password: 'test', username: null, firstname: null, lastname: null }, function(data) {
      ...
  });
  </code></pre>
  
  <p>The <strong>problem</strong> is that the parameters that are null (firstname, lastname, username) in my javascript call, they are not null in invoked controller action. They have string "null" value. I've already tried with undefined values of parameters in my javascript but it doesn't help.</p>
  
  <p>If I specify only parameters that are not null (without null parameters) in my javascript call, the parameters in my action are transferred correctly.</p>
  
  <p>How should I pass <strong>null parameters</strong> in my $getJSON call that will be correctly transffered to controller action or what should I do on MVC side?</p>