将div从父网站复制到iframe中的textarea

Question

In the Google Translator I've made a second instance of Google Translate with

var makediv = document.createElement("secondinstance");
makediv.innerHTML = '<iframe id="iframenaturalID" width="1500" height="300" src="https://translate.google.com"></iframe>';
makediv.setAttribute("id", "iframeID");
var getRef = document.getElementById("gt-c");
var parentDiv = getRef.parentNode;
parentDiv.insertBefore(makediv, getRef);

And I'm trying to copy text from auto-correction of the first instance to the textarea of the second instance:

I'm trying this (this code works if I just copy html within the Chrome inspector{using [0] or [1] to select elements with the same IDs}, however it's only possible to use two instances of the translator with iframe embedding):

setInterval(function() {
    var childAnchors1 = window.parent.document.querySelectorAll("#spelling-correction > a");
    var TheiFrameInstance = document.getElementById("iframeID");
    TheiFrameInstance.contentWindow.document.querySelectorAll("#source").value = childAnchors1.textContent;
}, 100);

But the console says that it cannot read property "document" of undefined at eval, and says that the problem is in this line:

  TheiFrameInstance.contentWindow.document.querySelectorAll("#source").value = childAnchors1.textContent;

I've tried embedding another website, and it also didn't work. I also tried to call iframe by "iframenaturalID", and tried to write TheiFrameInstance.contentWindow.document.querySelectorAll without the contentWindow , but nothing seems to work. I would very much appreciate any help.

Answer 1

Had similar problem recently trying to access iframe. Unfortunately it is impossible IF it is a cross-domain. Read more: Get element from within an iFrame

Hope it helps.

Answer 2

Ok, I made it work with a different method of creating iframe:

var a = document.createElement('iframe');
a.src = "https://translate.google.com"; 
a.id = "iframenaturalID";
a.width = "1000";
a.height = "500";
document.querySelector('body').appendChild(a)

And (copying textcontent from the correction div to the iframe textarea):

let iframe = document.getElementById("iframenaturalID");
setInterval(function() {
let source = iframe.contentWindow.document.getElementById("source");
let destination = window.parent.document.querySelector("#spelling-correction > a");


source.value = destination.textContent;
     }, 100);

Now it does what I tried to do, however I still get mistake message: Uncaught TypeError: Cannot set property 'value' of null at eval , which points at this line: source.value = destination.textContent; . It's not a big problem though, but still it's strange that it returns this mistake...