In git we can use following command to achieve it:

git merge --strategy-option theirs

But I couldn't figure out a way in nodegit: http://www.nodegit.org/api/repository/#mergeBranches

repo.mergeBranches("master.min", "master", null, merge.PREFERENCE.FASTFORWARD_ONLY);

A file favor enum is present

http://www.nodegit.org/api/merge/#FILE_FAVOR

But repo.mergeBranches() expects PREFERENCE enum. How do I pass FILE_FAVOR enum for merge.

http://stackoverflow.com/questions/34671270/nodegit-resolve-merge-conflict-in-favor-of-theirs