title: What does colon mean in jQuery when used inside of .trigger?
body: <p>I looked at <a href="http://api.jquery.com/trigger/" rel="nofollow">http://api.jquery.com/trigger/</a> and the examples did not answer my question. I am looking at some code and would like to know what this block of code is doing. </p>
  
  <pre><code>$(document).on('click', '#SubmitQuery', function(event) {
              event.preventDefault();
              $(document).trigger('filter:submit');
          });
  </code></pre>
  
  <p>Specifically, what does the colon inside of that trigger function do? For complete context, here is what filter is (I assume that the 'filter' inside of the trigger function refers to that filter object):</p>
  
  <pre><code>var filter = {
      init: function() {
          $(document).on('keypress', '#Filter', debounce(function(event) {
              if (event.keyCode == 13) {
                  $(document).trigger('filter:text');
              }
          }, 300));
  
          $(document).on('click', '#ClearFilter', function(event) {
              event.preventDefault();
              $('#FilterText').val('');
              $('#FilterText').focus();
              $(document).trigger('filter:clear');
          });
  
          $(document).on('change', '.filterSection [type=checkbox]', function(event) {
              var group = $(this).parents('[data-filter-group]').attr('data-filter-group');
              var $checkboxes = $('[data-filter-group=' + group + '] [type=checkbox]');
  
              if ($checkboxes.length &gt; 0) {
                  if ($checkboxes.filter(':checked').length === 0) {
                      $(this).prop('checked', true);
                  }
              }
          });
  
          $(document).on('click', '#SubmitQuery', function(event) {
              event.preventDefault();
              $(document).trigger('filter:submit');
          });
  
          $("#Filter").focus();
      }
  };
  </code></pre>