Geolocate Address with Google Maps API. Have used this code in WordPress admin on a few projects. Not overly generalized or documented in this version.

Geocode-Address-Google-Maps-API

/*
 *
 * Adds Geolocate button for Locations CPT custom address field
 * On button click, gathers address field components and looks up the geolocation with google
 * maps api.
 *
 * DEPENDENCIES:
 * must load //maps.googleapis.com/maps/api/js?sensor=false&key=<YOUR-API-KEY>
 */
/* jshint ignore:start */
;(function($,window,undefined){

	var $fld; // geolocation coordinates field as jquery object
	var err_msgs = {
		bad_addrs: "Not enough address info entered to lookup geo-coordinates",
		lookup_failed: "Geocoding lookup failed. Please verify address values",
		over_limit: "Google Maps Error: OVER LIMIT"
		};

	function getAddress(){
		var addr =   $('input[name="cfs[input][17][value]"]').val()
        ,city = $('input[name="UNDEFINED"]').val()
        ,state = $('input[name="UNDEFINED"]').val()
        ,zip = $('input[name="UNDEFINED"]').val()
        ,city_st_zip = $('input[name = "cfs[input][19][value]"]').val();

    if( city_st_zip === '' ){
  		if( city == '' && state == '' && zip == '' ){
  			return false;
  		}else{
    		city_st_zip = addr + city + ', ' + state + ' ' + zip;
  		}
    }

		var address = addr + ', ' + city_st_zip;
		console.log(address);
		return address;
	}

	// return geocode input field jquery obj
	function $geoinput(){
		return $('input[name="cfs[input][32][value]"]');
	}

	function clear_geo_field(){
		$geoinput().val('');
	}

	// ready
	$(function(){
		var address;
		var btn_html = '<button id="geobtn" style="height:25px;padding:3px;font-size:14px;">Geolocate Address</button';
		$fld = $geoinput();

		//resize input field
		$fld.width(300);

		//add button
		$fld.parent().append(btn_html);
		$("#geobtn").on('click',function(evt){
			evt.preventDefault();

			address = getAddress();
			if( !address ){
				alert(err_msgs.bad_addrs);
				return false;
			}

			var geocoderRequest = {address:address, region:'us'};
			var geocoder = new google.maps.Geocoder();

			// callback func for geocoder
			var geoCallback = function(geocoderResultArray, status){
				var r = geocoderResultArray;
				//console.log(gra=geocoderResultArray, "status=" + status);

				switch(status){
					case google.maps.GeocoderStatus.ZERO_RESULTS:
					case google.maps.GeocoderStatus.INVALID_REQUEST:
						alert(err_msgs.lookup_failed + " (zero results)");
						break;
					case google.maps.GeocoderStatus.ERROR:
						alert("Google maps Error");
						break;
					case google.maps.GeocoderStatus.OVER_QUERY_LIMIT:
						alert(err_msgs.over_limit);
						break;
					case google.maps.GeocoderStatus.REQUEST_DENIED:
					case google.maps.GeocoderStatus.UNKNOWN_ERROR:
						console.warn("Error looking up map search input:" + status);
						break;

					case google.maps.GeocoderStatus.OK:
						if( r.length > 0 ){
							// create comma-separated lat/lng string
							var ll = String(r[0].geometry.location.lat()) + ','
									+ String(r[0].geometry.location.lng());

							// set geo field's value
							$geoinput().val(ll);

						}else{
							alert(err_msgs.lookup_failed);
						}

				}
				if( status !== google.maps.GeocoderStatus.OK )
					clear_geo_field();

			};
			//
			// == Execute the maps geocode request ==
			//
			geocoder.geocode(geocoderRequest, geoCallback);

			return false; // stop event propagation

		});// on.('click')
	});//doc ready
}(jQuery,window));
/* jshint ignore:end */