author: Krasimir Tsonev

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GoogleMaps JS API: address to coordinates transformation

When we are talking about maps, Google is an absolute leader. Their GoogleMaps tool is free, well documented and works really good. What I didn't find directly in the documentation is how to get the exact location based on plain text. I.e. to convert an address to google.maps.LatLng object. That's why I wrote a simple function that did this job.
The page here demonstrates the method. It contains an input element, button and a map. Type something in the field and press search.

Step 1: Initialize the map


	var mapHolder = document.getElementById("map-holder");
	map = new google.maps.Map(
		mapHolder, 
		{
			zoom: 3,
			mapTypeId: google.maps.MapTypeId.ROADMAP
		}
	);
	map.setCenter(new google.maps.LatLng(43.229195, 27.872314));

Step 2: Calling the method

I simply attached a listener to the onclick event of the button. The addressToLocation function accepts the address (as plain text) and a callback function which will operate with the results.

	document.getElementById("search").onclick = function() {
		var address = document.getElementById("text").value;
		log("Address: " + address, true);
		addressToLocation(address, changeMapLocation);
	}
	

Step 3: Create google.maps.LatLng object based on the field's value

The method uses the google.maps.Geocoder object of the GoogleMaps API. At the end it sends the results to the callback function.

	function addressToLocation(address, callback) {
		var geocoder = new google.maps.Geocoder();
		geocoder.geocode(
			{
				address: address
			}, 
			function(results, status) {
				
				var resultLocations = [];
				
				if(status == google.maps.GeocoderStatus.OK) {
					if(results) {
						var numOfResults = results.length;
						for(var i=0; i 0) {
					callback(resultLocations);
				} else {
					callback(null);
				}
			}
		);
	}
	

Step 4: Process the results

The callback function accepts only one parameter. It is actually an array of objects. Every object has three properties:

	{
		text:...(String),
		addressStr:...(String),
		location:...(google.maps.LatLng)
	}
	
The function outputs all the locations in a div container, pans the map and adds markers for every item in the array.

	function changeMapLocation(locations) {
		if(locations && locations.length) {
			log("Num of results: " + locations.length);
			var numOfLocations = locations.length;
			for(var i=0; i" + locations[i].location.toString() + "");
				var marker = new google.maps.Marker({
					map: map,
					position: locations[i].location
				});
			}
			map.panTo(locations[0].location);
			map.setZoom(8);
		} else {
			log("Num of results: 0");
		}
	}
	
The full source code is available here.
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