title: jquery autocomplete special char trigger
body: <p>i have the following problem: </p>
  
  <p>i must make a special autocomplete with jquery triggered by char "@"</p>
  
  <p>the problem is that if i begin the textbox with @ it works but if i enter @ after i write some chars it doesn't work.</p>
  
  <p>how it must work:
  -i write some text an i want to add someone from "utilizatoriJson",
  -to add someone from "utilizatoriJson" i must press the @ key and an autocomplete dropdown must apear,
  -after i select someone from dropdown or i type a full label from dropdown it must put space and let me continue my message</p>
  
  <p>how can i do this ?</p>
  
  <p>code that i wrote :</p>
  
  <pre><code>var utilizatoriJson = &lt;%=utilizatoriJson%&gt;;
  
  $( '#textarea_mesaj_colaborare').autocomplete({
      source: utilizatoriJson
  
  })            .autocomplete( "instance" )._renderItem = function( ul, item ) {
      return $( "&lt;li&gt;" )
              .append( "&lt;a&gt;" + item.label + "&lt;/a&gt;" )
              .appendTo( ul );
  }
  $( '#textarea_mesaj_colaborare').autocomplete("disable");
  
  
  $('#textarea_mesaj_colaborare').keyup(function(){
      if ($('#textarea_mesaj_colaborare').val()[$('#textarea_mesaj_colaborare').val().length-1]==='@'){
          var inceput = $('#textarea_mesaj_colaborare').val().length;
  
          $( '#textarea_mesaj_colaborare').autocomplete("enable");
      }
  
  });
  </code></pre>