<!DOCTYPE html> <html> <body> <iframe></iframe> </body> <script> onload = function() { var i = document.querySelector("iframe"); var doc = i.contentDocument; doc.body.appendChild(doc.createTextNode("foo")); doc.designMode = "on"; while (doc.body.firstChild) { doc.body.removeChild(doc.body.firstChild); } }; </script> </html>