Open infoWindow of specific marker from outside Google Maps (V3)

Question

I can't seem to get my head around this problem:

I've got a map with (a lot of) markers (companies) that come from a generated XML file. Below the map, I want to show a (non-JavaScript-generated) list of all the companies that are displayed on the map. When I would click a company in the list, the map would pan to that specific marker and open an infoWindow. The thing is that I want the map and the list to be two separate things...

What would be the right way to tackle this problem? Thanks! Important is that all markerinfo is dynamic...

function initialize_member_map(lang) {
  var map = new google.maps.Map(document.getElementById("large-map-canvas"), {
    center: new google.maps.LatLng(50.85034, 4.35171),
    zoom: 13,
    mapTypeId: 'roadmap'
  });
  var infoWindow = new google.maps.InfoWindow;

  downloadUrl("/ajax/member-xml-output.php", function(data) {
  var xml = data.responseXML;
  var markers = xml.documentElement.getElementsByTagName("marker");
  var bounds = new google.maps.LatLngBounds();
  for (var i = 0; i < markers.length; i++) {
    var company = markers[i].getAttribute("company");
    var address = markers[i].getAttribute("address");
    var type = markers[i].getAttribute("type");
    var uid = markers[i].getAttribute("uid"); // Primary key of company table in MySQL
    var point = new google.maps.LatLng(
        parseFloat(markers[i].getAttribute("lat")),
        parseFloat(markers[i].getAttribute("lng")));
    var html = "<b>" + company + "</b> <br/>" + address;
    bounds.extend(point);    
    var marker = new google.maps.Marker({
      map: map,
      position: point,
      uid: uid // Some experiments, wanted to use this to target specific markers...
    });
    bindInfoWindow(marker, map, infoWindow, html); 
  }        
  map.setCenter(bounds.getCenter());
  map.fitBounds(bounds); 
});
}

function bindInfoWindow(marker, map, infoWindow, html) {
  google.maps.event.addListener(marker, 'click', function() {
    infoWindow.setContent(html);
    infoWindow.open(map, marker);
  });
}

function downloadUrl(url, callback) {
  var request = window.ActiveXObject ?
    new ActiveXObject('Microsoft.XMLHTTP') :
    new XMLHttpRequest;

  request.onreadystatechange = function() {
    if (request.readyState == 4) {
      request.onreadystatechange = doNothing;
      callback(request, request.status);
    } 
  };

  request.open('GET', url, true);
  request.send(null);
}
function doNothing() {}

Following the suggestions by Michal, I've tried the following, but am encountering two problems: my console tells me markers[index].getPosition is not a function and the first item in my list shows to be undefined. Can you please help?

//JavaScript Document
var map;
var markers = new Array();
var company_list;
function initialize_member_map(lang) {
  map = new google.maps.Map(document.getElementById("large-map-canvas"), {
    center: new google.maps.LatLng(50.85034, 4.35171),
    zoom: 13,
    mapTypeId: 'roadmap'
  });
  var infoWindow = new google.maps.InfoWindow;

  // Change this depending on the name of your PHP file
  downloadUrl("/ajax/member-xml-output.php?country=BE", function(data) {
    var xml = data.responseXML;
    markers = xml.documentElement.getElementsByTagName("marker");
    var bounds = new google.maps.LatLngBounds();
    for (var i = 0; i < markers.length; i++) {
      var company = markers[i].getAttribute("company");
      var address = markers[i].getAttribute("address");
      var type = markers[i].getAttribute("type");
      var uid = markers[i].getAttribute("uid");
      var point = new google.maps.LatLng(
          parseFloat(markers[i].getAttribute("lat")),
          parseFloat(markers[i].getAttribute("lng")));
      var html = "<b>" + company + "</b> <br/>" + address;
      bounds.extend(point); 
      var marker = new google.maps.Marker({
        map: map,
        position: point,
        uid: uid
      });
      bindInfoWindow(marker, map, infoWindow, html); 
      company_list += "<div onclick=scrollToMarker(" + i + ")>"+company+"</div>";
    }       
    map.setCenter(bounds.getCenter());
    map.fitBounds(bounds); 
    //display company data in html
    document.getElementById("company_list").innerHTML = company_list;
  });

}

function scrollToMarker(index) {
    map.panTo(markers[index].getPosition());
}

function bindInfoWindow(marker, map, infoWindow, html) {
  google.maps.event.addListener(marker, 'click', function() {
    infoWindow.setContent(html);
    infoWindow.open(map, marker);
  });
}

function downloadUrl(url, callback) {
  var request = window.ActiveXObject ?
      new ActiveXObject('Microsoft.XMLHTTP') :
      new XMLHttpRequest;

  request.onreadystatechange = function() {
    if (request.readyState == 4) {
      request.onreadystatechange = doNothing;
      callback(request, request.status);
    }
  };

  request.open('GET', url, true);
  request.send(null);
}
function doNothing(){
}

Answer 1

You are on the right track. You just need to create a separate global array for your Marker objects and push all created markers to this array. When you write out all your company data to html include a call with the index of the marker executed on click. Below is an example code. I used JSON as my data structure to hold company info instead of XML.

<html> 
<head> 
    <meta name="viewport" content="initial-scale=1.0, user-scalable=yes" /> 
    <meta http-equiv="content-type" content="text/html; charset=UTF-8"/> 
    <title>Google Maps Scroll to Marker</title> 

    <script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"></script> 

</head> 
<body onload="initialize()"> 

    <div id="map_canvas" style="width: 900px;height: 600px;"></div> 
    <div id="companies"></div>
    <script type="text/javascript"> 
        var map;
        //JSON of company data - equivalent of your XML 
        companies = {
            "data": [
            {
                "name": "Company 1",
                "lat": 42.166,
                "lng": -87.848 
            }, 
            {
                "name": "Company 2",
                "lat": 41.8358,
                "lng": -87.7128 
            },
            {
                "name": "Company 3",
                "lat": 41.463, 

                "lng": -88.870 
            },
            {"name":"Company 4",
            "lat":41.809, "lng":-87.790}		
            ]
        }
        //we will use this to store google map Marker objects 
        var markers=new Array();
        function initialize() {
            var chicago = new google.maps.LatLng(41.875696,-87.624207);
            var myOptions = {
                zoom: 9,
                center: chicago,
                mapTypeId: google.maps.MapTypeId.ROADMAP
            }
            map = new google.maps.Map(document.getElementById("map_canvas"),
                myOptions);
            listCompanies();
        }		 

        function listCompanies() {
            html = ""
        //loop through all companies
        for (i=0;i<companies.data.length;i++) {
        //get the maker postion
        lat  = companies.data[i].lat
        lng =  companies.data[i].lng

        //add google maps marker
        marker = new google.maps.Marker({
            map:map,
            position: new google.maps.LatLng(lat,lng),
            title: companies.data[i].name
        })
        markers.push(marker);
        html += "<div onclick=scrollToMarker(" + i + ")>"+companies.data[i].name+"</div>";
        }
        //display company data in html
        document.getElementById("companies").innerHTML =html;
        }

        function scrollToMarker(index) {
            map.panTo(markers[index].getPosition());
        }
</script>

</body> 
</html> 

Ok I added another solution for you - uising your code. This one uses your bindInfWindow function to bind the DOM (HTML) click event to open info window and scroll to marker. Please note that because you are loading companies dynamically the divs (or some other tags) that hold their names and ids must exist in the DOM BEFORE you start binding events to it - so the first function you need to execute is the one that renders companies HTML (not the map init). Please note I have not tested this one as I do not have your data..

//you must write out company divs first

<body onload="showCompanies()">



<script>
//JavaScript Document
var map;
//this is your text data
var markers = new Array();


//you need to create your company list first as we will be binding dom events to it so it must exist before marekrs are initialized
function showCompanies() {
 downloadUrl("/ajax/member-xml-output.php?country=BE", function(data) {
    var xml = data.responseXML;
    markers = xml.documentElement.getElementsByTagName("marker");

    for (var i = 0; i < markers.length; i++) {
      var company = markers[i].getAttribute("company");

      markerId = "id_"+i;

      company_list += "<div id="+markerId+">"+company+"</div>";
    }       

    //display company data in html
    document.getElementById("company_list").innerHTML = company_list;

    //now you are ready to initialize map
    initialize_member_map("lang")
  });
}

function initialize_member_map(lang) {
  map = new google.maps.Map(document.getElementById("large-map-canvas"), {
    center: new google.maps.LatLng(50.85034, 4.35171),
    zoom: 13,
    mapTypeId: 'roadmap'
  });




    var xml = data.responseXML;

    var bounds = new google.maps.LatLngBounds();
    //your company data was read in and is ready to be mapped
    for (var i = 0; i < markers.length; i++) {
      var infoWindow = new google.maps.InfoWindow;
      var company = markers[i].getAttribute("company");
      var address = markers[i].getAttribute("address");
      var type = markers[i].getAttribute("type");
      var uid = markers[i].getAttribute("uid");
      var point = new google.maps.LatLng(
          parseFloat(markers[i].getAttribute("lat")),
          parseFloat(markers[i].getAttribute("lng")));
      var html = "<b>" + company + "</b> <br/>" + address;
      bounds.extend(point); 
      var marker = new google.maps.Marker({
        map: map,
        position: point,
        uid: uid
      });
      //add the new marker object to the gMarkers array

      markerId = "id_"+i;
      bindInfoWindow(marker, map, infoWindow, html,markerId); 

    }       
    map.setCenter(bounds.getCenter());
    map.fitBounds(bounds); 


}

function scrollToMarker(index) {
    map.panTo(markers[index].getPosition());
}

function bindInfoWindow(marker, map, infoWindow, html, markerId) {
  google.maps.event.addListener(marker, 'click', function() {
    infoWindow.setContent(html);
    infoWindow.open(map, marker);
  });
  //bind onlcick events to the div or other object in html
  markerObj =  document.getElementById(markerId);
  //you can create DOM event listeners for the map
  google.maps.event.addDomListener(markerObj, 'click', function() {
    infoWindow.setContent(html);
    infoWindow.open(map, marker);
    map.panTo(marker.getPosition());
  });

}

function downloadUrl(url, callback) {
  var request = window.ActiveXObject ?
      new ActiveXObject('Microsoft.XMLHTTP') :
      new XMLHttpRequest;

  request.onreadystatechange = function() {
    if (request.readyState == 4) {
      request.onreadystatechange = doNothing;
      callback(request, request.status);
    }
  };

  request.open('GET', url, true);
  request.send(null);
}
function doNothing(){
}

</script>