This is a html/javasript snippet to embedd a google calender only with user consent

gcalender_consent.html

<div id="gcal">
	<p id="consent_text"><i> Beim Klick auf den Button "Kalender zeigen" wird ein eingebetter Kalender von Google geladen. Sie erklären sich damit mit der <a href="https://policies.google.com/privacy/update?hl=de" target="_blank" rel="noopener">Google Datenschutzerklärung</a> einverstanden und stimmen dieser explizit zu.</i></p>
	<button id="consent_button" class="btn btn-primary" style="margin-top: 20px;" onclick="show_cal()">Kalender zeigen</button>
</div>
<script type="text/javascript">
	function show_cal() {

		var cal_div = document.getElementById('gcal');

		var button = document.getElementById('consent_button');

		var consent_text = document.getElementById('consent_text');

		var cal = '<iframe src="https://calendar.google.com/calendar/embed?height=600&wkst=1&bgcolor=%23ffffff&ctz=Europe%2FVienna&src=Nm00M20zNXJvbjh2cTJjZDZqNWhndDNrdHNAZ3JvdXAuY2FsZW5kYXIuZ29vZ2xlLmNvbQ&color=%23D50000" style="border:solid 1px #777" width="800" height="600" frameborder="0" scrolling="no"></iframe>';

		cal_div.removeChild(button);

		cal_div.removeChild(consent_text);

		cal_div.innerHTML = cal;

	}
</script>