title: Puppeteer - How to fill form that is inside an iframe?
body: <p>I have to fill out a form that is inside an iframe, here the <a href="http://www.goodmanmfg.com/product-registration" rel="noreferrer">sample page</a>. I cannot access by simply using <code>page.focus()</code> and <code>page.type()</code>. I tried to get the form iframe by using <code>const formFrame = page.mainFrame().childFrames()[0]</code>, which works but I cannot really interact with the form iframe.</p>