Answers for "seeing whats in an iframe javascript"

how to get element in iframe using javascript

const iframe = document.getElementById("myIframe");

const iWindow = iframe.contentWindow;
const iDocument = iWindow.document;

// accessing the element
const element = iDocument.getElementsByTagName("p")[0];
element.style.color = "green";

js set iframe code

var html_string= "content";
document.getElementById('output_iframe1').src = "data:text/html;charset=utf-8," + escape(html_string);