Insert a countdown in each node based on a pre-existing date field I would like to put a countdown for each node using a field expiration date (whose values users have already entered).

I explain you my case:

My user publishes an event that have an expiration date (I already have many values for this field inserted by the users and some of them are of events still in progress).
I would like to insert a countdown in each page of the events, based on the expiration date inserted by the user and the date when the user has published the event on my website.

I tried with this module: field timer but I don't know how to do the connection between this module and the expiration date.

Thanks in advance for your help.
I assume you have two fields in one content type - countdown_date and expiration_date. Both values user has to insert manually. And after submit action, you want to assign expiration date to both fields, yes?

Read about hook_node_submit(). In your MYMODULE_node_submit($node, $form, &amp;$form_state) you can check the type of content, then assign expiration_date to countdown_date. This method works with save and preview's action.

For more detailed answer I need more details about these fields.