YouTube.js/examples/auth/README.md

Cookies

const innertube = await Innertube.create({
  cookie: '...'
});

YouTube TV OAuth2 (Limited)

Due to recent changes by Google, OAuth2 sign-in only works when using the TV client. This method is no longer recommended - please use cookies instead.

// Fired when waiting for the user to authorize the sign in attempt.
innertube.session.on('auth-pending', (data) => {
  // data.verification_url contains the authorization URL.
  // data.user_code contains the code to enter on the website.
});

// Fired when authentication is successful.
innertube.session.on('auth', ({ credentials }) => {
  // Do something with the credentials, eg; save them in a database.
  console.log('Sign in successful');
});

// Fired when the access token expires.
innertube.session.on('update-credentials', ({ credentials }) => { /** do something with the updated credentials. */ });
  
await innertube.session.signIn(/* credentials */);

An example can be found here.

Cache Credentials

If you don't want to start the sign-in flow every time you initialize the session, you can cache the credentials. Note that this SHOULD NOT be used in production, save your credentials in a database/file instead and pass them to Session#signIn(creds?) when signing in.

// If you use this, the next call to signIn won't fire 'auth-pending' instead just 'auth'
await innertube.session.oauth.cacheCredentials();

Note: When using cached credentials, you are still required to make a call to Session#signIn().

Sign Out

The sign-out method may be used to sign out of the current session. This removes and revokes the credentials.

await innertube.session.signOut();

// if you don't want to sign out of the current session
// and only want to delete the cached credentials, use:
await innertube.session.oauth.removeCache();