modified /site/modules/MarkupLeafletMap/InputfieldLeafletMapMarker.js for Processwire. Takes values from custom fields to do the geocoding

InputfieldLeafletMapMarker.js

/**
 * Display a Leaflet Map and pinpoint a location for InputfieldLeafletMapMarker
 *
 */

var InputfieldLeafletMapMarker = {

	options: {
		zoom: 9, 
		draggable: true, 
		center: null
	},	


	init: function(mapId, lat, lng, zoom, mapType, provider) {

		var options = InputfieldLeafletMapMarker.options; 

		if(zoom < 1) zoom = 9; 
		//options.center = new google.maps.LatLng(lat, lng); 	
		options.zoom = parseInt(zoom); 

		
		var map = L.map(document.getElementById(mapId)). setView([lat, lng], options.zoom); 	

		L.tileLayer.provider(provider).addTo(map);

		var coder = L.Control.Geocoder.nominatim(),
			geocoder = L.Control.geocoder({
				geocoder: geocoder, placeholder: ''
			})/*.addTo(map)*/

		var marker = L.marker(
			[lat,lng],
			{draggable: options.draggable}
			
		).addTo(map); 

		var $map = $('#' + mapId);
		//var $latlng = $map.siblings(".InputfieldLeafletMapMarkerLatLng").find("input[type=text]");
		var $lat = $map.siblings(".InputfieldLeafletMapMarkerLat").find("input[type=text]");
		var $lng = $map.siblings(".InputfieldLeafletMapMarkerLng").find("input[type=text]");
		var $addr = $map.siblings(".InputfieldLeafletMapMarkerAddress").find("input.address"); 
		var $addrJS = $map.siblings(".InputfieldLeafletMapMarkerAddress").find("input.addressJS"); 
		var $toggle = $map.siblings(".InputfieldLeafletMapMarkerToggle").find("input[type=checkbox]");
		var $zoom = $map.siblings(".InputfieldLeafletMapMarkerZoom").find("input[type=number]");
		var $notes = $map.siblings(".notes");
		var $setAddress = $map.siblings(".InputfieldLeafletMapMarkerSetAddress").find("#setAddress");
		var $latlng = '';

/*
		$( ".InputfieldLeafletMapMarkerAddress" ).on( "click", function() {
		  	$(".leaflet-control-geocoder.leaflet-control").toggleClass("leaflet-control-geocoder-expanded");
		  	setTimeout(function() { $('input.undefined').focus() }, 300);


		});
*/		
		
		$lat.val(marker.getLatLng().lat);
		$lng.val(marker.getLatLng().lng);
		$zoom.val(map.getZoom()); 

		$zoom.change(function(event) {
			map.setZoom($zoom.val());
			map.setView(marker.getLatLng());

		});

		$lat.change(function(event) {

			marker.setLatLng([$lat.val(),$lng.val()]);
			map.setView(marker.getLatLng(), 9);

			coder.reverse(marker.getLatLng(), map.options.crs.scale(map.getZoom()), function(results) {
	            var r = results[0];
	            if (r) {
	            
	                $addr.val(r.name);
	                
			
	            }
        	})
		 	
		});


		$lng.change(function(event) {

			marker.setLatLng([$lat.val(),$lng.val()]);
			map.setView(marker.getLatLng(), 9);
			coder.reverse(marker.getLatLng(), map.options.crs.scale(map.getZoom()), function(results) {
	            var r = results[0];
	            if (r) {
	            
	                $addr.val(r.name);
	                
			
	            }
        	})
		 	
		 	
		});


		var markGeocode = geocoder.markGeocode = function(result) {
		    marker.setLatLng(result.center);
		    map.fitBounds(result.bbox);
		    $lat.val(result.center.lat);
		    $lng.val(result.center.lng);
		    $addr.val(result.name);
		};


		marker.on('dragend', function(event) {
		    var result = marker.getLatLng();  
		    $lat.val(result.lat);
		    $lng.val(result.lng);

		    //reverse geocoding displays in the adress field
		    coder.reverse(marker.getLatLng(), map.options.crs.scale(map.getZoom()), function(results) {
	            var r = results[0];
	            if (r) {
	            
	                $addr.val(r.name);
	            }
        	})

		});

		map.on('zoomend', function(event){
			$zoom.val(map.getZoom()); 
		})

		$setAddress.on('click', function(event){
			event.preventDefault();
			var combAddress = $('#Inputfield_address').val() + ' ' + $('#Inputfield_postcode').val() + ' ' + $('#Inputfield_city').val();
			
			coder.geocode(combAddress, function(results) {
				// var result = results[0];
				markGeocode(results[0]);
				// map.setZoom(17);
			});

		});
		/*
	
		google.maps.event.addListener(map, 'zoom_changed', function() {
			$zoom.val(map.getZoom()); 
		}); 

		$addr.blur(function() {
			if(!$toggle.is(":checked")) return true;
			var geocoder = new google.maps.Geocoder();
			geocoder.geocode({ 'address': $(this).val()}, function(results, status) {
				if(status == google.maps.GeocoderStatus.OK && results[0]) {
					var position = results[0].geometry.location;
					map.setCenter(position);
					marker.setPosition(position);
					$lat.val(position.lat());
					$lng.val(position.lng());
					$addrJS.val($addr.val()); 
				}
				$notes.text(status); 
			});
			return true;	
		}); 

		$zoom.change(function() {
			map.setZoom(parseInt($(this).val())); 
		}); 

		$toggle.click(function() {
			if($(this).is(":checked")) {
				$notes.text('Geocode ON');
				// google.maps.event.trigger(marker, 'dragend'); 
				$addr.trigger('blur');
			} else {
				$notes.text('Geocode OFF');
			}
			return true;
		});

		// added by diogo to solve the problem of maps not rendering correctly in hidden elements
		// trigger a resize on the map when either the tab button or the toggle field bar are pressed

		// get the tab element where this map is integrated
		var $map = $('#' + mapId); 
		var $tab = $('#_' + $map.closest('.InputfieldFieldsetTabOpen').attr('id'));
		// get the inputfield where this map is integrated and add the tab to the stack
		var $inputFields = $map.closest('.Inputfield').find('.InputfieldStateToggle').add($tab);

		$inputFields.on('click',function(){
			// give it time to open
			window.setTimeout(function(){
				google.maps.event.trigger(map,'resize');
				map.setCenter(options.center); 
			}, 200);
		});
		*/
	}
};


$(document).ready(function() {
	$(".InputfieldLeafletMapMarkerMap").each(function() {
		var $t = $(this);
		InputfieldLeafletMapMarker.init($t.attr('id'), $t.attr('data-lat'), $t.attr('data-lng'), $t.attr('data-zoom'), $t.attr('data-type'), $t.attr('data-provider')); 
	}); 
});