Develop Reference

Check if user device's GPS is on

I am developing an app using jQuery Mobile with PHP. I am not using Phonegap or other frameworks. I need to find user's geolocation. If user device's GPS is off, then I cant get a location. now I need to find user device's GPS is on or off.
this is what i using now.
function getLocation() {
if (navigator.geolocation) {
navigator.geolocation.getCurrentPosition(showPosition);
} else {
x.innerHTML = "Geolocation is not supported by this browser.";
}
}
function showPosition(position) {
var lat=position.coords.latitude;
var long=position.coords.longitude;
}

You can call this function on load
// Function to get location
function getLocation(){
navigator.geolocation.getCurrentPosition(function (pos) {
var lat = pos.coords.latitude;
var lng = pos.coords.longitude;
if (lat == null) {
alert("GPS not activated!");
} else {
alert("Latitude: "+ lat + " , Longitude: " + lng );
}
});
}

There is no way to check if the device has a GPS module or if it has it enabled through the browser's API. Your laptop will, for example, try to estimate the position based on the IP address with very poor accuracy.
You can, however, use a trick that will likely be good enough for many applications: instead of using the getCurrentPosition(), use the watchPosition() function with an options object { enableHighAccuracy: true } and set a threshold of accuracy that the measurement has to reach for you to accept it as most likely a result based on the GPS module.
What happens when you start to listen to the watchPosition() with enableHighAccuracy set to true is that if GPS module is available, the API will let it know that you're trying to get a measurement and after up to a few seconds the accuracy distance will go from very high (often thousands of meters - based on IP address, cell tower triangulation, etc.) to a very low (few meters - based on the GPS) and that means that the GPS kicked in. If the accuracy stays at hundreds or thousands of meters, it probably means that there is no GPS module available.
Here's the documentation for the GeolocationCoordinates object (the result within the callback passed to the watchPosition()) which comes with the accuracy field. I wrote a longer post that also contains a code snippet showing how I use the API within React.

I just solved this one. I am using:
navigator.geolocation.getCurrentPosition(successCallback, errorCallback, {maximumAge: 60000});
In the successCallback i written the codes for what it should do once I got the positions and in the error callback i wrote a simple alert message to prompt the user to turn the GPS on.

I Implemented This In Real World Project
KMaps-API GPS.js
<script>
function getLocationw() {
if (navigator.geolocation) {
navigator.geolocation.getCurrentPosition(showPositionw);
} else {
x.innerHTML = "Something Is Wrong";
}
}
function showPositionw(position) {
lat = position.coords.latitude;
if(lat != null){
document.write('<center><div class="alert alert-info" role="alert"> Please Turn On Your GPS </div></center>')
}
}
getLocationw();
</script>

navigator.geolocation.getCurrentPosition() doesn't work

I am trying to get the latitude and longitude of my current location using geolocation. Extremely similar code was working until recently, and I can't figure out why it stopped working. It is no longer setting the variables latitude or longitude. When I walk through the js code, the getCurrentPosition() method is skipped and I'm not sure why. Bizarrely, if I put an alert box in the getCurrentPosition() method, it will get and display the latitude and longitude correctly... I have no idea why it does that.
var gl;
try {
if (typeof navigator.geolocation === 'undefined'){
gl = google.gears.factory.create('beta.geolocation');
} else {
gl = navigator.geolocation;
}
} catch(e) {}
var latitude;
var longitude;
if (gl) {
gl.getCurrentPosition(
function (position) {
latitude = position.coords.latitude;
longitude = position.coords.longitude;
//alert("got the lat & long - lat=" + latitude + ", lng=" + longitude);
},
function (error) {
alert("Error getting geolocation:" + error);
}
);
} else {
alert("Geolocation services are not supported by your web browser.");
}
I then go on to set some markers on a map using the Google Maps API.
Thank you very much,
Peter
EDIT
Here the code on JSFiddle showing the weird behavior:
http://jsfiddle.net/JtmCV/

I just tried your jsfiddle and it worked fine (Chrome 19 on Win 7), so I can't see why it should be causing problems.
Having said that, I'd strongly recommend switching to use navigator.geolocation.watchPosition instead of navigator.geolocation.getCurrentPosition. I recently did some work on a geolocation system and found getCurrentPosition can return unreliable cached positions, even if you use the options parameter to specify a low maximumAge value.
My latest version stops the watch after one of the following is true:
the fifth position has been returned
the accuracy is under 100m
the time since the watch began is over 30 seconds

Mobile Safari not accepting HTML5 Meter input value

I'm creating an app that tracks your elevation. Currently IOS is one of the only devices to support the Altitude parameter so it's vital to get it working in mobile Safari. The altitude will be printed in two location on page, in a text element and also in the Meter element so there is a visual representation of your current altitude.
Generating the altitude hasn't been an issue but what I haven't had any success with getting the altitude to store in the Meter's value. Something to note is the Mobile Safari doesn't support the Meter element so I am using a polyfill to get it to work at all.
You can get the general idea of what i'm trying to do here: http://jsfiddle.net/qF9hh/
Notice the geolocation coords are commented out, but they do work if you were to test it on an IOS device.
So my question is, how do I get the Altitude coordinate to store in the Meter??

something like this might work better
var worked = false;
$("button").click(function () {
worked = false;
if (navigator.geolocation) {
navigator.geolocation.getCurrentPosition(success, error);
} else {
error('not supported');
}
}).load();​
function error(msg){
alert(typeof(msg) = "string" ? msg : "error!");
}
function success(pos){
if(worked)return; // to prevent firing twice in firefox
worked = true;
var meter = $("#high");
if(pos.altitude === null){
error("Altitide not supported");
return;
}
meter.val(pos.altitude);
meter.text(pos.altitude + "/" + meter.attr("max"));
}
Jsfiddle

Browser's geolocation displaying two initial locations

I wrote a map page that uses geolocation to detect the user's location. When the user clicks a button, this javascript is called:
if (navigator.geolocation) {
wpid = navigator.geolocation.watchPosition(function (position) {
setUserPosition(position, "Your location", pollUserPosition);
},
function() { handleNoGeolocation(true); },
{ enableHighAccuracy: false, maximumAge: 30000, timeout: 10000 }
);
}
From what I understand, watchPosition will start polling the user's location until it's told to stop. This is done by calling clearWatch and passing in the wpid from the watchPositon call. setUserPosition will create a marker on the map based upon the location in position. When I test this page in mobile safari sometimes I get two initial locations marked on the map. Does anyone know why I'd get two locations returned and how I can only return one? Is it because a location is returned using both the cell connection and the wifi connection on the iPhone?
Update:
As a test, I turned off WiFi on the phone and tested the map page again. Unfortunately, I'm still getting two initial locations when I call watchPosition.

with watchPosition, you will get updated position information on the callback if the position data changes either by device movement or if more accurate geo information arrives.
So if you want only ONE position try using the:
navigator.geolocation.getCurrentPosition
This should only return ONE position. Have you tried that already?

How to make a "did you mean" link with suggestions, in google maps api?

I'm trying to make a web application with google maps api, that gives directions. Right now, It gives directions fine unless the user types in something wrong, it either doesn't show anything or it tries to figure it out and gives the wrong address. I want to make functionality where if the address is not recognized it has "did you mean" and then make a suggestion that's close to what you were trying to enter. I couldn't find anything in the google code that talked about that, but I'm wondering if anyone knows if it's possible, and how I can do it?
Thanks!

loadFromWayPoints() draws polyline only if the inputs provided to it maps to any definite point on the earth. You can avoid the confusion to function by fixing your from point in form of latitude and longitude, instead of address. Then using following function you may create Did you mean for To point if multiple points returned for toInput.
Code is self explanatory. If you dont understand. Reply in comment.
One of the point you want to plot should return definite point from google geocoder system.
In my I used the from point as definite point. And had it coordinates with me. So there is no chance of getting
geo.getLocations(toInput, function (result){
//map.clearOverlays();
if (result.Status.code == G_GEO_SUCCESS) {
// ===== If there was more than one result, "ask did you mean" on them all =====
if (result.Placemark.length > 1) {
document.getElementById("textualdirectionscontainer").innerHTML = "Did you mean:";
// Loop through the results
for (var i=0; i<result.Placemark.length; i++) {
var p = result.Placemark[i].Point.coordinates;
document.getElementById("textualdirectionscontainer").innerHTML += "<br>"+(i+1)+": <a href='javascript:place(" +p[1]+","+p[0]+")'>"+ result.Placemark[i].address+"<\/a>";
}
}
// ===== If there was a single marker =====
else {
document.getElementById("textualdirectionscontainer").innerHTML = "";
var p = result.Placemark[0].Point.coordinates;
toLatLang = new GLatLng(p[1], p[0]);
// place(p[1],p[0]);
directionsPanel = $('textualdirectionscontainer');
directionsPanel.getElements('div').each(function(item) {
item.dispose();
});
directions.clear();
directions.loadFromWaypoints([hotelLatLng.toString(), toLatLang.toString()], {getPolyline:true});
/*var gp = directions.getPolyline();
map.addOverlay(gp); */
}
}
});