The Autosave module automatically saves a node after a period of time. Content types that can be autosaved as well as the period of time a node is autosaved, is configurable.
Autosaved nodes are are saved as a snap shot of the form.
NOTE: this version of autosave only works for single form (of selected node type) on a page.
Port [Autosave] module to D8 https://www.drupal.org/node/2825115