The W3C’s browser-based, JavaScript Geolocation API is excellent as a one-size-fits-all interface, but that approach comes at a price and it can cause some serious limitations when it comes to implementing more stringent professional, commercial and government use-cases.
Challenges with the default Geolocation API. One of the primary limitations is the Geolocation API does not tell you how it got a location. All locations are lumped together in a black box. Let me explain. On a smartphone or tablet, location data comes from one of three places: the GPS chipset, the cellular provider’s Location Service, or the browser’s Location Service. The W3C Geolocation API simply lumps these data points together. The end result is typically seen by the end user as significant and disturbingly wild jumps back and forth in the reported location, sometimes over large distances. A key to minimizing these fluctuations is to gain back control and understand which location provider created the latitude and longitude point.
Cordova-plugin-advanced-geolocation. The good news is that Android, in particular, has a very detailed API called LocationManager for examining geolocation data that comes from the device. And, even better news for JavaScript developers is that the API, along with its access to all on-device GPS and Network location providers, has been exposed thru a Cordova plugin that is available here: https://github.com/Esri/cordova-plugin-advanced-geolocation.
What geolocation data is available? With this plugin you’ll be able to programmatically differentiate between the following geolocation data as well as get access to GPS satellites meta data:
- Real-time GPS location – This is data from the on-board GPS or some devices will allow it to be the location data from an external GPS that is connected to the device via bluetooth.
- Cached GPS location – Most devices cache the last-known GPS location and it’s persistent even when the device is restarted.
- Real-time Network location triangulation – this is completely dependent on devices and cellular service providers. It may require WiFi to be turned on. It also may not be available in all countries or regions.
- Cached Network location – Most devices cache the last-known network-based location and it’s persistent even when the device is restarted.
Use cases. With this plugin, you can now use your JavaScript skills to implement the following use cases and much more. For example, I’ve always wanted to play with the Satellite data to make a 3D map of the satellites using JavaScript. This plugin provides a huge advantage to developers building applications for capturing a single location such as field survey work as well as the following use cases and others that I haven’t thought of:
- Determine a static outdoors location and only use GPS.
- While indoors turn on only network location. Do not use GPS.
- While in an urban area, use network location to get initial location before the GPS warms up and then turn off network location and only use GPS
- Compare the differences between GPS and Network locations
- …???
How does this plugin help minimize location fluctuations? This plugin comes with a configuration option for turning on a buffer. You can set the size of the buffer, each new geolocation from the device will be added to it, and then plugin will determine the geometric center based on all the locations in the buffer.
Are there any other advanced plugins? Yes, some Cordova plugins are focused on being activity based and will detect if you are walking, stopped, moving, etc. These plugins tend to work as apps that can be backgrounded. Feel free to browse the Cordova plug-in directory here.