is it possible to retrieve the current value in sharepoint list item before save

I have a sharepoint list. On the edit form of list item i have a custom action button to send the mail containg the contents of the list columns . If the user changes any value in a column and then clicks the custom action button, the new column value is not retrived. Is it possible to retrieve the edited value before clicking save on edit form.

I am using _spGetQueryParam('id') to retrive the current id.