Attach a popup to a marker instance | NMaps GL JS Docs

Attach a Popup to a Marker and display it on click.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Attach a popup to a marker instance</title>
<meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no" />
<script src="https://cdn.ndrive.com/nmapsgl/v.1.6.8/nmaps-gl.js"></script>
<link href="https://cdn.ndrive.com/nmapsgl/v.1.6.8/nmaps-gl.css" rel="stylesheet" />
<style>
	body { margin: 0; padding: 0; }
	#map { position: absolute; top: 0; bottom: 0; width: 100%; }
</style>
</head>
<body>
<style>
#marker {
background-image: url('https://nmaps-gl.ndrive.com/nmaps-gl-js/assets/washington-monument.jpg');
background-size: cover;
width: 50px;
height: 50px;
border-radius: 50%;
cursor: pointer;
}
 
.nmapsgl-popup {
max-width: 200px;
}
</style>
 
<div id="map"></div>
 
<script>
	// TO MAKE THE MAP APPEAR YOU MUST ADD YOUR ACCESS TOKEN
	nmapsgl.accessToken = '<your access token here>';
	
const monument = [-77.0353, 38.8895];
const map = new nmapsgl.Map({
container: 'map',
style: 'Streets',
center: monument,
zoom: 15
});
 
// create the popup
const popup = new nmapsgl.Popup({ offset: 25 }).setText(
'Construction on the Washington Monument began in 1848.'
);
 
// create DOM element for the marker
const el = document.createElement('div');
el.id = 'marker';
 
// create the marker
new nmapsgl.Marker(el)
.setLngLat(monument)
.setPopup(popup) // sets a popup on this marker
.addTo(map);
</script>
 
</body>
</html>