getting variable value from inside function js - javascript

I am trying to get user current location and pass those latitude/longitude coordinates to a map. The map will be used as a website background image.
I was partially successful with this code:
navigator.geolocation.getCurrentPosition(showPosition);
function showPosition(position) {
xss =position.coords.latitude +
"," + position.coords.longitude;
}
var position = [32.5590985,35.8415147];
Now I want the value of xss to be inside this variable:
var position = [32.5590985,35.8415147];
basically I was trying to get the values from the function but without success.
How should I go about getting a value from inside the function?
HTML
<div id="googlemaps"></div>
JS Code
navigator.geolocation.getCurrentPosition(showPosition);
function showPosition(position) {
xss =position.coords.latitude +
"," + position.coords.longitude;
}
var position = [32.5590985,35.8415147];
function initialize() {
var myOptions = {
zoom: 17,
streetViewControl: false,
scaleControl: false,
mapTypeId: google.maps.MapTypeId.ROADMAP
};
map = new google.maps.Map(document.getElementById('googlemaps'),
myOptions);
latLng = new google.maps.LatLng(position[0], position[1]);
map.setCenter(latLng);
marker = new google.maps.Marker({
position: latLng,
map: map,
draggable: false,
animation: google.maps.Animation.DROP
});
}
google.maps.event.addDomListener(window, 'load', initialize);

How about you set the value of position variable from inside the showPosition function?
var position;
navigator.geolocation.getCurrentPosition(showPosition);
function showPosition(pos) {
position = [pos.coords.latitude, pos.coords.longitude];
}

Assuming navigator.geolocation.getCurrentPosition is asynchronous, this looks like a classic "Get results from an asynchronous request" problem. Please see https://stackoverflow.com/a/14220323/380487 for a detailed answer.

Related

Adding Javascript Functions to Load Google Maps C# WPF

I am trying to integrate Google Maps into a WebBrowserControl in my C# WPF program. The map loads in the control and centers on the correct latitude and longitude, however I am having a couple of errors. First of all, the map loads and after a couple of seconds I get an error box appear;
Secondly, when I am trying to add a marker on the location of the latitude and longitude, I get an error even before the map loads at all. Here is my code so far;
mapWebBrowser.NavigateToString(#"<html xmlns=""http://www.w3.org/1999/xhtml"" xmlns:v=""urn:schemas-microsoft-com:vml"">
<head>
<meta http - equiv = ""X-UA-Compatible"" content = ""IE=edge""/>
<meta name = ""viewport"" content = ""initial-scale=1.0, user-scalable=no""/>
<script type = ""text/javascript""
src = ""http://maps.google.com.mx/maps/api/js?sensor=true&language=""es"" ></script>
<script src = 'http://google-maps-utility-library-v3.googlecode.com/svn/trunk/markerclusterer/src/markerclusterer.js'>
</script><script type = ""text/javascript"">
function initialize() {
var latlng = new google.maps.LatLng(" + latitude + ", " + longitude + #");
var myOptions = {
zoom: 16,
center: latlng,
mapTypeId: google.maps.MapTypeId.ROADMAP
};
var map = new google.maps.Map(document.getElementById(""map_canvas""), myOptions);
}
function addMarker( Lat, Long) {
var latLng = new google.maps.LatLng(Lat, Long);
marker = new google.maps.Marker({
position: latLng,
draggable: false,
animation: google.maps.Animation.DROP,
});
markers.push(marker);
var markerCluster = new MarkerClusterer(map, markers)
}
</script>
</head>
<body onload = ""initialize()"" >
<div id=""map_canvas"" style=""width:100%; height:100%""></div>
</body>
</html>");
This is the function I am attempting to use to add a marker onto the map;
function addMarker( Lat, Long) {
var latLng = new google.maps.LatLng(Lat, Long);
marker = new google.maps.Marker({
position: latLng,
draggable: false,
animation: google.maps.Animation.DROP,
});
markers.push(marker);
var markerCluster = new MarkerClusterer(map, markers)
}
Which I call in C#;
mapWebBrowser.InvokeScript("addMarker", new object[] { latitude, longitude } );
Unfortunately as I stated before both methods are causing issues.
I believe there was a change in Google's APIs back in June and they now require authentication for google maps. I don't see your API key being supplied anywhere. I would suggest you try your HTML/javascript in the browser or where you can sniff the requests and the responses and see what's going on.
If you still can't solve your problem. You may use Script Errors Suppressed too. Then this window will disappear.
webBrowser1.ScriptErrorsSuppressed = true;

Doing a Google Maps reverse geocode and displaying the result as part as HTML content inside an infowindow

I have put together this script (note: I'm using jQuery 1.11.2) that gets lat long coordinates from a PHP operation (used for something else) and displays a map with a customized marker and infowindow that includes HTML for formatting the information that is displayed.
<script src="https://maps.googleapis.com/maps/api/js?v=3.20&sensor=false"></script>
<script type="text/javascript">
var maplat = 41.36058;
var maplong = 2.19234;
function initialize() {
// Create a Google coordinate object for where to center the map
var latlng = new google.maps.LatLng( maplat, maplong ); // Coordinates
var mapOptions = {
center: latlng,
zoom: 3,
mapTypeId: google.maps.MapTypeId.ROADMAP,
scrollwheel: false,
streetViewControl: false,
zoomControl: false,
mapTypeControl: false,
disableDoubleClickZoom: true
};
map = new google.maps.Map(document.getElementById("map-canvas"),mapOptions);
// CREATE AN INFOWINDOW FOR THE MARKER
var content = 'This will show up inside the infowindow and it is here where I would like to show the converted lat/long coordinates into the actual, human-readable City/State/Country'
; // HTML text to display in the InfoWindow
var infowindow = new google.maps.InfoWindow({
content: content,maxWidth: 250
});
var marker = new google.maps.Marker( {
position: latlng,
map: map,
title: "A SHORT BUT BORING TITLE",
});
google.maps.event.addListener(marker, 'click', function() {
infowindow.open(map,marker);
});
infowindow.open(map,marker);
}
google.maps.event.addDomListener(window, 'load', initialize);
</script>
What I'm trying to achieve is to do a reverse geocode on the coordinates stored in the latlng variable and get back the results of that in a "City, State, Country" format and insert that into the HTML for the informarker stored in the "content" variable.
Have tried multiple approaches without success. Please note that I've deliberately left out the reverse geocoding script I tried to use for clarity purposes.
Edit: I've adjusted the script presented here to comply with the rules about it being clear, readable and that it actually should work. I also include a link to a CodePen so that you can see it in action: Script on CodePen
Regarding including the script for reverse geocoding, what I did was a disaster, only breaking the page and producing "undefined value" errors. I'd like to learn the correct way of doing this by example, and that's where the wonderful StackOverflow community comes in. Thanks again for your interest in helping me out.
Use a node instead of a string as content , then you may place the geocoding-result inside the content, no matter if the infoWindow is already visible or not or when the result is available(it doesn't even matter if the InfoWindow has already been initialized, a node is always "live").
Simple Demo:
function initialize() {
var geocoder = new google.maps.Geocoder(),
latlng = new google.maps.LatLng(52.5498783, 13.42520);
map = new google.maps.Map(document.getElementById('map-canvas'), {
zoom: 18,
center: latlng
}),
marker = new google.maps.Marker({
map: map,
position: latlng
}),
content = document.createElement('div'),
infoWin = new google.maps.InfoWindow({
content: content
});
content.innerHTML = '<address>the address should appear here</address>';
google.maps.event.addListener(marker, 'click', function() {
infoWin.open(map, this);
});
geocoder.geocode({
location: latlng
}, function(r, s) {
if (s === google.maps.GeocoderStatus.OK) {
content.getElementsByTagName('address')[0].textContent = r[0].formatted_address;
} else {
window.alert('Geocoder failed due to: ' + status);
}
});
}
google.maps.event.addDomListener(window, 'load', initialize);
html,
body,
#map-canvas {
height: 100%;
margin: 0px;
padding: 0px
}
<script src="https://maps.googleapis.com/maps/api/js?v=3"></script>
<div id="map-canvas"></div>
Here's how I would do it:
function reverseGeocoder(lat, lng, callback) {
var geocoder = new google.maps.Geocoder();
var point = new google.maps.LatLng(parseFloat(lat), parseFloat(lng));
geocoder.geocode({"latLng" : point }, function(data, status) {
if (status == google.maps.GeocoderStatus.OK && data[0]) {
callback(null, data[0].formatted_address);
} else {
console.log("Error: " + status);
callback(status, null);
}
});
};
And basically you would call the function like:
reverseGeocoder(lat, lng, function(err, result){
// Do whatever has to be done with result!
// EDIT: For example you can pass the result to your initialize() function like so:
initialize(result); // And then inside your initialize function process the result!
});

Update markers with current position on Google Map API

I am learning to use javascript right now with Rails and I'm having some issues with updating my markers according to my current position using AJAX. I believe the ready page:load is not running the updated coords that have been attached as a data-attribute, coords since the page is not technically reloading. How can I use my current position data and update it with events with longitude/latitude values?
var map;
$(document).on('ready page:load', function() {
if ("geolocation" in navigator) {
myMap.init();
var coords = $('#map-canvas').data('coords');
if (coords){
myMap.addMarkers(coords);
}
}
});
myMap.init = function() {
if(navigator.geolocation){
var mapOptions = {
zoom: 14,
mapTypeId: google.maps.MapTypeId.ROADMAP
};
map = new google.maps.Map(document.getElementById('map-canvas'), mapOptions);
navigator.geolocation.getCurrentPosition(function(position){
var pos = new google.maps.LatLng(position.coords.latitude, position.coords.longitude);
var infoWindow = new google.maps.InfoWindow({
map: map,
position: pos
});
var marker = new google.maps.Marker({
position: new google.maps.LatLng(position.coords.latitude, position.coords.longitude),
map: map
});
map.setCenter(pos);
var latitude = position.coords.latitude;
var longitude = position.coords.longitude;
$.ajax({
url:"/all_events",
method: "GET",
data: {
latitude: latitude,
longitude: longitude
},
dataType: 'script'
});
});
} else {
document.getElementById('map-canvas').innerHTML = 'No Geolocation Support.';
}
};
myMap.addMarkers = function(coords){
var image = "http://maps.google.com/mapfiles/ms/icons/yellow-dot.png"
coords.forEach(function(coord){
var myMarker = new google.maps.Marker({
position: new google.maps.LatLng(coord.latitude, coord.longitude),
map: map,
icon: image
});
});
}
In order to make your script work in the way you want please try out the following steps:
Put your foreach loop in a function and call it at the end of your successive AJAX callbacks.
Load the AJAX once the Google Maps have finished loading completely. If Google Maps library has not finished loading than you wont be able to create a Google LatLng object, this is what is probably happening over here.
Hope this would help

How to add Markers on Google maps v3 API asynchronously?

I've been following the official documentation on how to add markers on the map so far
Nevertheless, I can see only one marker at a time max. If I try to add another one, then it doesn't work (I can't even see the first one).
My process is the following:
I initialize gmaps api:
jQuery(window).ready(function(){
//If we click on Find me Lakes
jQuery("#btnInit").click(initiate_geolocation);
});
function initiate_geolocation() {
if (navigator.geolocation)
{
var script = document.createElement("script");
script.type = "text/javascript";
script.src = "https://maps.googleapis.com/maps/api/js?key=AIzaSyBbfJJVh0jL1X9b7XFDcPuV7nHD1HlfsKs&sensor=true&callback=initialize";
document.body.appendChild(script);
navigator.geolocation.getCurrentPosition(handle_geolocation_query, handle_errors);
}
else
{
yqlgeo.get('visitor', normalize_yql_response);
}
}
Then, I display it on the appropriate div. But when it comes to make the AJAX call, in order to get my locations of the different markers I'd like to display, It just doesn't work properly. Here is the code with a simple map displayed (since that's the only thing working for me so far).
function handle_geolocation_query(position){
var mapOptions = {
zoom: 14,
center: new google.maps.LatLng(position.coords.latitude, position.coords.longitude),
mapTypeId: google.maps.MapTypeId.SATELLITE
}
alert('Lat: ' + position.coords.latitude + ' ' +
'Lon: ' + position.coords.longitude);
$('#map-canvas').slideToggle('slow', function(){
var map = new google.maps.Map(document.getElementById("map-canvas"), mapOptions);
});
$.when( getLakes(position.coords.latitude, position.coords.longitude)).done(function(results) {
// InitializeGoogleMaps(results);
if(results)
var data = results.map(function (lake) {
//Check if the lake has any open swims, if not, the button will not be clickable and an alert will pop up
if (lake.available>0)
clickable=true;
else
clickable=false;
return {
name: lake.name,
fishs: lake.fisheryType,
swims: lake.swims,
dist: lake.distance,
lat: lake.latitude,
long: lake.longitude,
id: lake.id,
avail: lake.available,
clickable: clickable,
route: Routing.generate('lake_display', { id: lake.id, lat: position.coords.latitude, lng: position.coords.longitude})
}
});
var template = Handlebars.compile( $('#template').html() );
$('#list').append( template(data) );
} );
};
So I'd like to add markers after the AJAX call. I've set up a function that I should call in the when()
function InitializeGoogleMaps(results) {
};
to display the markers in a foreach loop but nope, can't make it work. It looks like this :
CentralPark = new google.maps.LatLng(37.7699298, -122.4469157);
marker = new google.maps.Marker({
position: location,
map: map
});
Any help would be great !
Thanks
The main issue is that the map variable is declared only in the scope of the anonymous callback on slideToggle. First of all declare at the top-level function scope.
function handle_geolocation_query(position){
var map,
mapOptions = {
zoom: 14,
center: new google.maps.LatLng(position.coords.latitude, position.coords.longitude),
mapTypeId: google.maps.MapTypeId.SATELLITE
}
...
Then change the slideToggle callback to initialise the variable instead of redeclaring:
$('#map-canvas').slideToggle('slow', function(){
map = new google.maps.Map(document.getElementById("map-canvas"), mapOptions);
});
Then you should pass map as a second parameter to your InitializeGoogleMaps function and call it using InitializeGoogleMaps(results, map). See where this gets you and hit me back with any questions.

Is JavaScript Closure the Solution here, How to use it?

I have google maps implemented and I am getting latitude and longitude, I want thse values to be used outside of the google maps function. I can add them to the DOM only when I call these variables within the google maps code. How can I use these variables outside to google maps function.
On click of the maps, I need to append these latitude and longitude values to the URL as a querystring.
I am not sure how Closures work exactly. Can someone please help me adding these latitude and longitude values to the querystring outside of google maps initilaize() function.
Below is my code;
<script>
function initialize() {
var mapOptions = {
center: new google.maps.LatLng(44.397, -122.644),
zoom: 4,
mapTypeId: google.maps.MapTypeId.ROADMAP
}
var map = new google.maps.Map(document.getElementById("map_canvas"), mapOptions);
var marker = new google.maps.Marker({
position: new google.maps.LatLng(44.397, -122.644),
map: map,
draggable: true
});
google.maps.event.addListener(map, 'mousemove', function ques(event) {
var lat_value = event.latLng.lat();
var lon_value = event.latLng.lng();
document.getElementById("llat").value = lat_value;
document.getElementById("llon").value = lon_value;
});
google.maps.event.addListener(map, 'click', function cclick() {
})
}
</script>
<script>
$(function () {
// Access functions and variables defined in google maps initialize() function here
if(document.location.href.indexOf('?') == -1) {
window.location = window.location + "?lat_value";
}
});
</script>
FIDDLE
You don't need to use a JS closure here. You don't even need to write the handler outside of the scope of that initialize method. Just do it the same way you did the mousemove handler:
google.maps.event.addListener(map, 'click', function (e) {
var lat_value = e.latLng.lat();
var lon_value = e.latLng.lng();
window.location = window.location.href.split('?')[0]
+ "?lat_value=" + lat_value
+ "&long_value=" + lon_value;
});
In general though, if you wanted to have access to your mapOptions variable outside of initialize, just define it in the outer-scope (i.e. do the var mapOptions declaration before function initialize).

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