title: toggle() function working without passing the 2nd parameter .
body: <p>Hey guys i am just building the simplest of drop down menus and i am using a very small snippet of Jquery , i coded it myself . There is a small problem i am having though. checkout my Jquery code : </p>
  
  <pre><code>$('#r-menu').on('click', function () {
      $('#menu').toggle(function () {
          $(this).css({
              'display': 'block'
          });
      }, function () {
          // $(this).css({ 'display' : 'none' }); 
      }); // end toggle
  }); 
  </code></pre>
  
  <p><a href="http://jsfiddle.net/xw1p3Lsu/" rel="nofollow">Fiddle here</a>. </p>
  
  <p>now , why is the toggle() working without me adding the secound function . my code works just fine , my question is why is the menu toggling between display:none and display:block , when i have not explicitly specified the 2nd parameter of toggle() ? This would be my 1st and most important question . </p>
  
  <p>My 2nd question and more of a supplementary one , notice how when you click on a menu, when toggling , the menu slides in from the top left and enlarges , where is this effect coming from ? i have not specified slideup() or slidein() anywhere ? is there some effect internally being applied ? </p>
  
  <p>I would appreciate an explanation on this difficulty of mine. </p>
  
  <p>Thank you. </p>
  
  <p>Alexander. </p>