javascript - What does passport authenticate do on callback? -

i using passport js in express project. first route below goes , creates user in db , returns second callback route.

what passport.authenticate('facebook'... ) doing in callback router?

if i using in restful api (no session), can leave out passport.authenticate in callback?

app.get('/auth/facebook', passport.authenticate('facebook'));  app.get('/auth/facebook/callback',   passport.authenticate('facebook', { successredirect: '/',                                       failureredirect: '/login' })); 

what passport.authenticate('facebook'... ) doing in callback router?

that required facebook redirect user after approval. if remove that, after user authenticate facebook there won't redirected site and/or user authenticating see error.

if i using in restful api (no session), can leave out passport.authenticate in callback?

according passport.js documentation if wish facebook authentication need following routes:

//to send user facebook app.get('/auth/facebook', passport.authenticate('facebook'));  //this facebook return user token, refreshtoken, profile app.get('/auth/facebook/callback',   passport.authenticate('facebook', { successredirect: '/',                                       failureredirect: '/login' })); 

what passport authenticate on callback?

the verify callback facebook authentication accepts accesstoken, refreshtoken, , profile arguments. profile contain user profile information provided facebook.

the passport.js documentation source of how things work. there tutorials show how fb authentication workflow take place.