title: unaffix event for Bootstrap affix?
body: <p>I want to combine the affix plugin with the bootstrap navbar-fixed-top class. So far I have got it working then when I scroll past the navbar it gets fixed. But when I scroll back up I want it to go back into static state again. I have seen some code I think from older bootstrap versions and a <code>unaffix</code> event. Why is it gone? Can I create one? Or how to accomplish what I am trying here?</p>
  
  <pre><code>navbar_secondary = $( '.navbar-secondary:first' );
  
  navbar_secondary.affix( {
      offset: {
          top: function () {
              return (this.top = navbar_secondary.offset().top )
          }
      }
  } );
  
  navbar_secondary.on( 'affix.bs.affix', function () { // this is actually the wrong event for this. I want this to fire when its *not* affixed
      console.log('affix');
      navbar_secondary.removeClass( 'navbar-fixed-top' ).addClass( 'navbar-not-fixed' );
  } );
  
  navbar_secondary.on( 'affixed.bs.affix', function () {
      console.log('affixed');
      navbar_secondary.removeClass( 'navbar-not-fixed' ).addClass( 'navbar-fixed-top' );
  } );
  </code></pre>