Any experience with Typescript/ES6 class Strategies?

[rbeer]

Hello,

do yo have any experience with strategies as ES6 classes?

I wrote a Telegram strategy in Typescript. The problem is that the .success, etc. augmentations don't work when I use the strategy by its name, i.e. passport.authenticate('telegram-widget'). If I use the instance though, the strategy works as expected.

const tgStrategy = new TelegramWidgetStrategy({ botToken }, (_, user, done) => {
  log.info(user);
  return done(null, user, 'Authentication good');
});

// tgStrategy.name === 'telegram-widget'

passport.use(tgStrategy);

app.use(passport.initialize());

app.get(
  '/tg-auth',
  // passport.authenticate('telegram-widget') - TypeError: this.success is not a function
  // full stack trace, below
  passport.authenticate(tgStrategy), // this works
  (req, res) => {
    res.json(req.user);
  }
);

The problem originates from:

passport/lib/middleware/authenticate.js

Lines 188 to 196 in c872f74

	var strategy, prototype;
	if (typeof layer.authenticate == 'function') {
	strategy = layer;
	} else {
	prototype = passport._strategy(layer);
	if (!prototype) { return next(new Error('Unknown authentication strategy "' + layer + '"')); }
	strategy = Object.create(prototype);
	}

I've tried to compile to es5, but with the same result.

My use case doesn't allow me to simply use the working approach, as it itself is a plugin to a forum which uses the name approach.

What I'm really asking is: Where do I spend my time; making this compatible and PR here or just rewrite the strategy in es5 prototypal?

TypeError: this.success is not a function
    at TelegramWidgetStrategy.verified (/home/rbeer/code/passport-telegram-widget/dist/lib/strategy.js:20:18)
    at TelegramWidgetStrategy.verify (/home/rbeer/code/passport-telegram-widget-demo/index.js:46:10)
    at TelegramWidgetStrategy.authenticate (/home/rbeer/code/passport-telegram-widget/dist/lib/strategy.js:52:14)
    at attempt (/home/rbeer/code/passport-telegram-widget-demo/node_modules/passport/lib/middleware/authenticate.js:369:16)
    at authenticate (/home/rbeer/code/passport-telegram-widget-demo/node_modules/passport/lib/middleware/authenticate.js:370:7)
    at Layer.handle [as handle_request] (/home/rbeer/code/passport-telegram-widget-demo/node_modules/express/lib/router/layer.js:95:5)
    at next (/home/rbeer/code/passport-telegram-widget-demo/node_modules/express/lib/router/route.js:137:13)
    at Route.dispatch (/home/rbeer/code/passport-telegram-widget-demo/node_modules/express/lib/router/route.js:112:3)
    at Layer.handle [as handle_request] (/home/rbeer/code/passport-telegram-widget-demo/node_modules/express/lib/router/layer.js:95:5)
    at /home/rbeer/code/passport-telegram-widget-demo/node_modules/express/lib/router/index.js:281:22

[rbeer]

Alright, got it; and it was just me not seeing the wood for the trees.

Two things:

1. Arrow functions bad
   Arrow functions don't have a reference on this - ever.

Don't do this

verified: VerifiedCallback = (err, user, info) => {}

Do that

verified(err, user, info) {}

2. Bind the verified callback to the class

this.verify(req, user, this.verified.bind(this));

Otherwise the this reference inside the callback will be undefined - or worse something entirely else.

The wild days of ES5. I guess Crockford was right, after all. 😄