如何访问加载的 iframe 中的元素？

Question

I have a website with a donorbox button. When it's clicked, an iframe is added to the page as a modal. I want to access the elements in that iframe but I get an error Cannot read property 'click' of null when I try to click one of the buttons with a simple document.getElementsByClassName('db_button')[0].click(); command.

Debugging in the console, I also get the same message until I inspect the element and then it seems to work fine. What am I doing wrong?

Answer 1

firstly, get your iframe element

document.getElementById('iframeId') or document.getElementsByTagName("iframe")

the second expression will get a list object, get the iframe you need with index.

secondly, get inner document by this

a.contentDocument || a.contentWindow.document

then do your search inside iframe's document.