var doc = document.getElementById('myIframe').contentWindow.document;
doc.open();
doc.write("<html>....</html>");
doc.close();
But chrome started to show the warning from 2018, therefore, you can modify as following way:
document.getElementById('myIframe')
.contentWindow.document.documentElement.innerHTML = "<html>....</html>";
If you want to add jQuery in iframe:
var iframeWindow = document.getElementById('myIframe').contentWindow;
iframeWindow.$ = function (selector) {
return jQuery(selector, iframeWindow.document.body);
};
