Flow type definitions for Puppeteer prevent using default export?

Consider puppeteer's launch() method. The usage guidelines in the Puppeteer readme recommend to use const puppeteer = require('puppeteer') and then puppeteer.launch():

const puppeteer = require('puppeteer');

(async () => {
  const browser = await puppeteer.launch();
  const page = await browser.newPage();
  await page.goto('https://example.com');
  await page.screenshot({path: 'example.png'});

  await browser.close();
})();

And Puppeteer itself exports an instance, which seems to further confirm the default export is meant to be used:

module.exports = new Puppeteer(__dirname, preferredRevision, isPuppeteerCore);

However, the Flow type definitions for puppeteer ≥1.12 use declare export function launch() and don't include a default export, so Flow requires me to write import { launch } from "puppeteer" instead of import puppeteer from "puppeteer".

But using the named import yields TypeError: Cannot read property '_launcher' of undefined. Similarly, we can confirm this doesn't work with a simple test (Node v10.15.0, puppeteer 1.19.0):

const puppeteer = require("puppeteer");
puppeteer.launch();  // works

const { launch } = require("puppeteer");
launch();  // TypeError: Cannot read property '_launcher' of undefined

(Presumably this is because const { launch } = gives me an unbound method — this === undefined when called.)

Attempt 2: In Flow you can also use a namespaced import import * as puppeteer from "puppeteer", but it seems this explicitly forgoes access to the default export, instead yielding TypeError: puppeteer.launch is not a function.

(I'm less familiar with TypeScript, but the DefinitelyTyped defs for Puppeteer also use export function launch() rather than a default export. That said, they seem intended to be used with import * as puppeteer from "puppeteer", although I'm not sure why this would work when it doesn't in Flow; perhaps a difference in how TypeScript handles ES6 modules?)

So, am I holding it wrong, or are the Flow type definitions wrong? (In which case, how has nobody else encountered this problem?)

Recommended topics

Hot tags