title: jQuery UI autocomplete after input something
body: <p>I want to autocomplete user name after input '@'(at sign).</p>
  
  <p>form_html.erb:</p>
  
  <pre><code>  &lt;div class="form-group ui-widget"&gt;
      &lt;div class="col-sm-5"&gt;
        &lt;%= f.text_area :content, rows: 5, placeholder: '...', class: 'form-control', id: "tags", 'data-article-id': @article.id.to_s %&gt;
      &lt;/div&gt;
    &lt;/div&gt;
  </code></pre>
  
  <p>this is my coffeescript:</p>
  
  <pre><code>$ -&gt;
    id = $("#tags").data("article-id")
    $("#tags").autocomplete
      source:  '/articles/' + id + '/autocomplete.json'
      minLength: 1
  </code></pre>
  
  <p>current appearance：</p>
  
  <p><a href="https://i.stack.imgur.com/eTYat.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/eTYat.png" alt="enter image description here"></a></p>
  
  <p>I want to input the "@"(at sign) then auto-complete user name.</p>
  
  <p>Please tell me if you have good ideas, Thanks in advance!</p>