{{#if desc}}
   {{desc}}
{{else}}
   No description
{{/if}}
examples/handlebars/handlebars_if.html
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">

  <script src="jquery.js"></script>
  <script src="handlebars.min.js"></script>
  <script src="handlebars_data.js"></script>
  <script src="handlebars_process.js"></script>

  <script id="text-template" type="text/x-handlebars-template">
    <h2>{{title}}</h2>
    <h3>{{description}}</h3>
    <ul>
    {{#each articles}}
    <li><a href="{{url}}">{{title}}</a>
        {{#if desc}}
           <br>{{desc}}
        {{else}}
           <br>No description
        {{/if}}
    </li>
    {{/each}}
    </ul>
  </script>
</head>
<body>
<div id="text"></div>
</body>
</html>