In your Wagtail, you sometimes may want to vary the template output depending on whether the page is being previewed or viewed live.

It might be as simple as adding a banner to clearly show that you are previewing a page or you might want to disable some tracking code during preview (Google Analytics for example).

Wagtail adds a variable is_preview to the request you can use to check this:

For example, if you have visitor tracking code such as Google Analytics in place on your site, it’s a good idea to leave this out when previewing, so that editor activity doesn’t appear in your analytics reports. Wagtail provides a request.is_preview variable to distinguish between preview and live.

So, in your template, you can do:

{% if not request.is_preview %}
{% endif %}