Why is the passport.authenticate('facebook'... ) necessary in the callback router?
It is essential for Facebook to redirect the user back to your site after authentication approval. Without it, users will not be redirected and may encounter errors during the authentication process.
If I am using this in a restful API without sessions, can I omit the passport.authenticate in the callback?
Based on the passport.js documentation, including passport.authenticate in the callback is required for Facebook authentication. The specified routes are needed for the authentication to function properly.
//to redirect user to facebook
app.get('/auth/facebook', passport.authenticate('facebook'));
//for facebook to return user with token, refreshToken, Profile
app.get('/auth/facebook/callback',
passport.authenticate('facebook', { successRedirect: '/',
failureRedirect: '/login' }));
What is the purpose of passport authenticate in the callback?
The verify callback during Facebook authentication accepts accessToken, refreshToken, and profile arguments. The profile includes user information retrieved from Facebook.
Referencing the extensive documentation provided by passport.js is highly recommended for understanding how the authentication process works. Additionally, there are tutorials available to guide users through the FB authentication workflow.