I have a scenario where I need to allow users to log into an application using either username or email address. Hence I need to match username with both username and email in users collection in a MongoDB.

To achieve I used $or condition to match two fields at once with findOne filter.

var user = await users.findOne({
        $or: [
          {
            username: req.body.username
          },
          {
            email: req.body.username
          }
        ]
      });