title: jquery datatables: how to clear column search filter
body: <p>I am using jquery <a href="https://datatables.net/" rel="nofollow">datatables</a> to make my table searchable. I have a dropdown that filters a gender column:</p>
  
  <pre><code>$("#genderDrop").on("change", function(e) {
      var gender = $(this).val();
  
      formTable.column(2).search(gender).draw();
  });
  </code></pre>
  
  <p>this works fine, but now I want to be able to remove the filter when the user selects "all" from the dropdown.  Here is my attempt:</p>
  
  <pre><code>$("#genderDrop").on("change", function(e) {
      var gender = $(this).val();
      if (gender != "all") {
          formTable.column(2).search(gender).draw();
      } else {
           formTable.column(2).search("").draw();
      }
  });
  </code></pre>
  
  <p>Instead of removing the filter this just searches for an empty string, but I can't work out how to change this so it removes the filter.  I also tried:</p>
  
  <pre><code>formTable.column(2).search("*").draw();
  </code></pre>
  
  <p>and &nbsp;</p>
  
  <pre><code>formTable.column(2).search().draw();
  </code></pre>
  
  <p>but without any success.</p>