如何全局创建异步/等待

Question

I want to use a variable globally that has an await, something like this:

(async () => {
  const browser = await puppeteer.launch({headless: false})
  const page = await browser.newPage();
})()

And later use it on all my functions:

async function login() {

  await page.goto(urls.login);
  await page.type('#username', user);
  await page.type('#password', pw);
  page.click('[type="submit"]');
  await page.waitForNavigation();

}

Running it I get this error:

ReferenceError: page is not defined.

There is some way to make it work?

Answer 1

Store the promise in the global variable:

const pagePromise = (async () => {
  const browser = await puppeteer.launch({headless: false})
  return browser.newPage();
})();

Then you can later use it like

async function login(page) {
  await page.goto(urls.login);
  await page.type('#username', user);
  await page.type('#password', pw);
  page.click('[type="submit"]');
  await page.waitForNavigation();
}
pagePromise.then(login).catch(console.error);

or

async function login() {
  const page = await pagePromise;
  await page.goto(urls.login);
  await page.type('#username', user);
  await page.type('#password', pw);
  page.click('[type="submit"]');
  await page.waitForNavigation();
}
login().catch(console.error);

Answer 2

Solutions here: https://github.com/tc39/ecmascript-asyncawait/issues/9

(async () => {
const browser = await puppeteer.launch({headless: false})
const page = await browser.newPage()

async function login() {

    await page.goto(urls.login, {waitUntil: 'networkidle2'});
    await page.type('#user', user);
    await page.type('#password', pw);
    await page.click('[type="submit"]');
    await page.waitForNavigation();
    await page.screenshot({path: 'after-login.png'});
}

login();

})()