HTML and CSS Reference
In-Depth Information
The first example calculates how far the user is from the birthplace of
Tim Berners-Lee. Although this example uses a single fixed point for
simplicity, the techniques involved will work just as well for more
advanced scenarios—working out how far apart two users of your
website are, for example.
You may remember, from school, working out the distance between two
points on a plane using the Pythagorean theorem. Calculating the distance
between two latitude/longitude points isn't quite as straightforward
because these aren't points on a flat surface, but points on a sphere.
Rather than learn all that
math for yourself, you can use
an excellent set of JavaScript
utilities from Chris Veness,
available at www.movabletype . This
library allows you to create
LatLon objects that have several useful methods available. Starting with
a blank HTML5 document, you can create the following page with five
simple steps.
Start with an empty HTML5 page with a link to the LatLon.js
library. All the JavaScript code goes in the empty init
<!DOCTYPE html>
<meta charset="utf-8">
<title>Geolocation 4</title>
<script src="LatLon.js"></script>
<script> function init() { } </script>
<body onload="init();">
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