iframe.iframef{ max-width:1400px; } var iframe = document.querySelector('.iframef'); var url = iframe.getAttribute('src'); iframe.setAttribute('src',url + '&host=' + document.location.hostname); iframe.onload = function() { iframe.contentWindow.postMessage('getElementSize', '*'); }; window.onresize = function() { iframe.contentWindow.postMessage('getElementSize', '*'); }; window.addEventListener( "message", (event) => { if (event.origin !== "https://deepblueseries.com"){return}else{ if(event.data.redirect){ window.location.href=event.data.redirect; } else if(event.data.size){ var size = event.data.size; iframe.setAttribute('height', size.height + 40 + 'px'); } } }, false, ); If you go for the latter, all