What's hook_node_view() alternative? I am using Drupal 8 Beta 14 and I want to edit the node object in teaser view mode. As hook_node_view is removed in Drupal 8. What's the alternative hook or some other way that I can use to edit the node? Is it hook_ENTITY_TYPE_view or hook_entity_view or some other thing?

Thank you.
hook_node_view() hasn't really been removed, the way it's invoked has just changed. As you mentioned, it's now handled by hook_ENTITY_TYPE_view().

So you can either use:

hook_entity_view()


or

hook_node_view()


The latter would make more sense if you're targeting nodes specifically.