Snippet: JS function to intialise a GMap with a marker and infoWindow

gmap_marker_info.js

function initMap() {
    // Office lat lang
    var officeLatLang = {
        lat: -25.363,
        lng: 131.044
    };

    // infoWindow content string
    var infoContent = '<p>55 Dangal Road,<br>' +
        'Vikas Nagar, Lucknow<br>' +
        'Uttarpradesh, 226022<br>' +
        'India</p>';

    // Initialise the infoWindow with the content string 
    var infowindow = new google.maps.InfoWindow({
        content: infoContent
    });

    // Initialise the map with required options
    var map = new google.maps.Map(document.getElementById('map'), {
        zoom: 4, // map zoom level
        center: officeLatLang, // coordinates to center on
        scrollwheel: false // prevent accidental scrolling of map
    });

    // Initialise the marker and add to map 
    var marker = new google.maps.Marker({
        position: officeLatLang, // marker coordinates
        map: map // map to place on
    });

    // Display infoWindow on marker click
    marker.addListener('click', function() {
        infowindow.open(map, marker);
    });

    // Display infoWindow onLoad
    infowindow.open(map, marker);
}