Advanced options


All the display functions take an optional refresh argument that when set to True will re-render timestamps every minute. If a different time interval is desired, pass the interval in minutes as the value of the refresh argument.

This option is useful for relative time formats such as the one returned by the fromNow() or fromTime() functions. For example, the date of a comment would appear as “a few seconds ago” when the comment was just entered, but a minute later it would automatically refresh to “a minute ago” without the need to refresh the page.

By default automatic refreshing is disabled.

Default Format

The format() function can be invoked without arguments, in which case a default format of ISO8601 defined by the moment.js library is used. If you want to set a different default, you can set the MOMENT_DEFAULT_FORMAT variable in the Flask configuration. Consult the moment.js format documentation for a list of accepted tokens.


By default dates and times are rendered in English. To change to a different language add the following line in the <head> section of your template(s), after the include_moment() line:

{{ moment.locale("es") }}

The above example sets the language to Spanish. Moment.js supports a large number of languages. Consult the documentation for the list of languages and their corresponding two letter codes.

This extension also supports auto-detection of the client’s browser language:

{{ moment.locale(auto_detect=True) }}

Custom locales can also be included as a dictionary:

{{ moment.locale(customizations={ ... }) }}

See the moment.js locale customizations documentation for details on how to define a custom locale.

Ajax Support

It is also possible to create Flask-Moment timestamps in Python code that is invoked from the client page through Ajax, without the use of Jinja templates:

timestamp = moment.create(datetime.utcnow()).calendar()

The moment variable is the Moment instance that was created at initialization time.

A timestamp created in this way is an HTML string that can be returned as part of a response. For example, here is how a timestamp can be returned in a JSON object:

return { 'timestamp': moment.create(datetime.utcnow()).format('L') }

The Ajax callback in the browser needs to call flask_moment_render_all() each time an element containing a timestamp is added to the DOM. The example application in the Flask-Moment GitHub repository demonstrates how this is done.

Subresource Integrity (SRI)

SRI is a security feature that enables browsers to verify that resources they fetch are not maliciously manipulated. To do so a cryptographic hash is provided that proves integrity.

SRI for the moment.js library is enabled by default. If you wish to use a version different than the one bundled with this extension, or want to host your own javascript, a separate hash can be provided.

Just add sri=<YOUR-HASH> when calling moment.include_moment(). If no SRI hash is provided when a custom moment.js version is used, then SRI verification is not used.

To disable SRI, pass sri=False in the include_moment() call.