sample-vanillajs-ajax.html

<script type="text/javascript">
document.addEventListener('DOMContentLoaded', function() {

	document.querySelectorAll('div.ccom_monitoring_task')
	.forEach(function(taskDiv) {

		taskDiv.innerHTML = '<img decoding="async" alt="spinner" src="/wp-includes/images/wpspin.gif">';

		let task = taskDiv.getAttribute('data-task');

		let request = new XMLHttpRequest();

		request.open(
		'POST', '/wp-admin/admin-ajax.php', true
		);

		request.onload = function() {
			if (this.status >= 200 && this.status < 400) {
				taskDiv.innerHTML = this.response;
			} else {
				alert('Response error');
			}
		};

		request.onerror = function() {
			alert('Connection error');
		};

		var data = new FormData;
		data.append('action', 'ccom_monitoring');
		data.append('task', task);
		request.send(data);

	});
});
</script>