JS alert without URL on the top of modal

popup.js

function silentAlert(messages) {
	let iframeElement = '<iframe style="display: none;" id="silent_alert"></iframe>';
	document.getElementsByTagName('body')[0].innerHTML += iframeElement;
	let ifrm = document.getElementById('silent_alert');
	ifrm = ifrm.contentWindow || ifrm.contentDocument.document || ifrm.contentDocument;
	ifrm.document.open();
	ifrm.document.write('<script>alert("' + messages + '");<\/script>');
	ifrm.document.close();
}