## Overview

This tutorial shows you how to display the geographic location of a device on a Google map, using
your browser's HTML5 Geolocation feature along with the Maps JavaScript API. The
geographic location will only display if the user has allowed location sharing.

When the user triggers the geolocation request, they will receive a prompt from the browser
for consent to access the device's location data. If the request fails, it could be because
location permissions were denied, or because the device couldn't determine its location.
This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

Below is a map that can identify the present location of the user's device.
<iframe src="https://geo-devrel-javascript-samples.web.app/samples/map-geolocation/app/dist/" allow="fullscreen; geolocation *;"></iframe>

The sample below shows the entire code you need to create this map.

### TypeScript

```typescript
// Note: This example requires that you consent to location sharing when
// prompted by your browser. If you see the error "The Geolocation service
// failed.", it means you probably did not give permission for the browser to
// locate you.
let map: google.maps.Map, infoWindow: google.maps.InfoWindow;

function initMap(): void {
  map = new google.maps.Map(document.getElementById("map") as HTMLElement, {
    center: { lat: -34.397, lng: 150.644 },
    zoom: 6,
  });
  infoWindow = new google.maps.InfoWindow();

  const locationButton = document.createElement("button");

  locationButton.textContent = "Pan to Current Location";
  locationButton.classList.add("custom-map-control-button");

  map.controls[google.maps.ControlPosition.TOP_CENTER].push(locationButton);

  locationButton.addEventListener("click", () => {
    // Try HTML5 geolocation.
    if (navigator.geolocation) {
      navigator.geolocation.getCurrentPosition(
        (position: GeolocationPosition) => {
          const pos = {
            lat: position.coords.latitude,
            lng: position.coords.longitude,
          };

          infoWindow.setPosition(pos);
          infoWindow.setContent("Location found.");
          infoWindow.open(map);
          map.setCenter(pos);
        },
        () => {
          handleLocationError(true, infoWindow, map.getCenter()!);
        }
      );
    } else {
      // Browser doesn't support Geolocation
      handleLocationError(false, infoWindow, map.getCenter()!);
    }
  });
}

function handleLocationError(
  browserHasGeolocation: boolean,
  infoWindow: google.maps.InfoWindow,
  pos: google.maps.LatLng
) {
  infoWindow.setPosition(pos);
  infoWindow.setContent(
    browserHasGeolocation
      ? "Error: The Geolocation service failed."
      : "Error: Your browser doesn't support geolocation."
  );
  infoWindow.open(map);
}

declare global {
  interface Window {
    initMap: () => void;
  }
}
window.initMap = initMap;
```

> [!NOTE]
> **Note:** Read the [guide](https://developers.google.com/maps/documentation/javascript/using-typescript.md.txt) on using TypeScript and Google Maps.

### JavaScript

```javascript
// Note: This example requires that you consent to location sharing when
// prompted by your browser. If you see the error "The Geolocation service
// failed.", it means you probably did not give permission for the browser to
// locate you.
let map, infoWindow;

function initMap() {
  map = new google.maps.Map(document.getElementById("map"), {
    center: { lat: -34.397, lng: 150.644 },
    zoom: 6,
  });
  infoWindow = new google.maps.InfoWindow();

  const locationButton = document.createElement("button");

  locationButton.textContent = "Pan to Current Location";
  locationButton.classList.add("custom-map-control-button");
  map.controls[google.maps.ControlPosition.TOP_CENTER].push(locationButton);
  locationButton.addEventListener("click", () => {
    // Try HTML5 geolocation.
    if (navigator.geolocation) {
      navigator.geolocation.getCurrentPosition(
        (position) => {
          const pos = {
            lat: position.coords.latitude,
            lng: position.coords.longitude,
          };

          infoWindow.setPosition(pos);
          infoWindow.setContent("Location found.");
          infoWindow.open(map);
          map.setCenter(pos);
        },
        () => {
          handleLocationError(true, infoWindow, map.getCenter());
        },
      );
    } else {
      // Browser doesn't support Geolocation
      handleLocationError(false, infoWindow, map.getCenter());
    }
  });
}

function handleLocationError(browserHasGeolocation, infoWindow, pos) {
  infoWindow.setPosition(pos);
  infoWindow.setContent(
    browserHasGeolocation
      ? "Error: The Geolocation service failed."
      : "Error: Your browser doesn't support geolocation.",
  );
  infoWindow.open(map);
}

window.initMap = initMap;
```

> [!NOTE]
> **Note:** The JavaScript is compiled from the TypeScript snippet.

[View example](https://developers.google.com/maps/documentation/javascript/examples/map-geolocation.md.txt)

## What is Geolocation?

Geolocation refers to the identification of the geographic location of a computing device
using a variety of data collection mechanisms. Typically, most geolocation services use network
routing addresses or internal GPS chips to determine this location. Geolocation is a
device-specific API. This means that browsers or devices must support geolocation in order to use
it through web applications.

## W3C Geolocation standard

Applications that want to perform geolocation must support the
[W3C Geolocation standard](http://dev.w3.org/geo/api/spec-source.html). Notice that the
sample code above determines the device's location through the W3C
`navigator.geolocation` API.

Sometimes websites use IP addresses to detect the location of a device, however this may only provide a
rough estimate of that location. W3C-standard APIs are the most fully-supported and most accurate, so they should be
prioritized over other geolocation methods.