title: passing a parameter in url ajax
body: <p>I have this code, how can I pass a parameter to data.php (data.php?q=) so when user digits something I can filter
  the data and retrieve just a subset of records?</p>
  <pre><code>var company;
  
  $(document).ready(function() {
  
  $('.select-ajax').multiselect({
      maxHeight: 400,
      buttonWidth: '100%',
      includeSelectAllOption: true,
      enableFiltering: true
  }); 
  
  $.ajax({
    type: 'GET',
    url: '/data.php',
    dataType: 'json',
    success: function(data) {
       $.each(data, function (i, item) {
           company = item.company;
           $('.select-ajax').append('&lt;option value=&quot;' + item.company + '&quot;&gt;' + item.company + '&lt;/option&gt;');
           console.log(item)
      });
      $('.select-ajax').multiselect('rebuild');
    },
    error: function() {
          alert('error loading items');
    }
   });
  
  $('.select-ajax').trigger( 'change' );
  
  }); 
  &lt;/script&gt;```
  </code></pre>