How to login in Puppeteer?

page.waitForNavigation(); waits for navigation after a click or any navigation action that triggers from the page. You should probably add the waitForNavigation() after the page.click().

await Promise.all([
  page.click('#loginSubmit'),
  page.waitForNavigation({ waitUntil: 'networkidle0' }),
]);

It will wait until both promises resolve.

So now your initial code would look like this:

const puppeteer = require('puppeteer');

async function main() {
  const browser = await puppeteer.launch({headless: false});
  const page = await browser.newPage();
  await page.setViewport({width: 1200, height: 720});
  await page.goto('https://www.daum.net', { waitUntil: 'networkidle0' }); // wait until page load
  await page.type('#id', CREDS.username);
  await page.type('#loginPw', CREDS.password);
  // click and wait for navigation
  await Promise.all([
    page.click('#loginSubmit'),
    page.waitForNavigation({ waitUntil: 'networkidle0' }),
  ]);
}

main();

Note: Answer aside, I cannot test this since I don’t have a login for daum.net and I cannot see the actual error you are facing. If you can try the solution provided above, and share the results, it’d be much more helpful.