Allows one to define a tag that subviews can append content to. Handy for letting subviews add resources to the head or footer, for example.
The layout - /views/layouts/default.html:
<!DOCTYPE html>
<html>
<head>
<title>The Title</title>
<link rel="stylesheet" href="/stylesheets/style.css" />
{% output "javascript" %}
<script src="/jquery.js"></script>
{% endoutput %}
</head>
<body>
{% block content %}{% endblock %}
</body>
</html>The view - /views/index.html:
{% extends "/layouts/default.html" %}
{% append "javascript" %}
<!-- Will be output beneath jquery.js -->
<script src="/index-script.js"></script>
{% endappend %}
{% block content %}
<div>
<p>The content</p>
</div>
{% endblock %}The output:
<html>
<head>
<title>The Title</title>
<link href="/stylesheets/style.css" rel="stylesheet">
<script src="/jquery.js"></script>
<!-- Will be output beneath jquery.js -->
<script src="/index-script.js"></script>
</head>
<body>
<div>
<p>The content</p>
</div>
</body>
</html>