title: How can I pass full form + extra data via jquery $.post?
body: <p>I send data with my form through jquery $.post to some PHP page, but now i want to add some extra data to this sent package.
  Here is my code:</p>
  
  <pre><code>    $.post("/settings/filter", $("#filter_form").serialize() , function(data,status,xhr)
      {
              my_data = data;
  
      }) 
  </code></pre>
  
  <p>I've tried to change it into </p>
  
  <pre><code>    $.post("/settings/filter", {$("#filter_form").serialize(), extra_variable:'extra1'} , function(data,status,xhr)
  </code></pre>
  
  <p>but it's wrong, how to do it?</p>