To submit a form with Node Puppeteer, we call click on the submit button.
For instance, we write
await page.goto("https://www.example.com/login");
await page.type("#username", "username");
await page.type("#password", "password");
await page.click("#submit");
await page.waitForNavigation();
to call goto to go to the page.
Then we call type to enter the values for the inputs with IDs username and password.
And then we call click to click the button with ID submit to submit the form.