html5 geolocation with fallback.

gistfile1.js

// geo-location shim

// currentely only serves lat/long

// doublecheck the ClientLocation results because it may returning null results

(function (geolocation) {

	if (geolocation) return;
	  
	var cache;
	var head;
	  
	geolocation = window.navigator.geolocation = {};
	geolocation.getCurrentPosition = function (callback) {
		    
		if (cache) callback(cache);

		head = head || document.head || document.getElementsByTagName('head')[0] || document.documentElement;

		var script = document.createElement('script');
		script.async = 'async';
		script.src = '//www.google.com/jsapi';
		script.onload = script.onreadystatechange = function (_, isAbort) {
			if ( isAbort || !script.readyState || /loaded|complete/.test( script.readyState ) ) {
				script.onload = script.onreadystatechange = null;
				if ( head && script.parentNode ) {
					head.removeChild( script );
				}
				script = void undefined;
				if ( !isAbort ) {
					// sometimes ClientLocation comes back null
					if (google.loader.ClientLocation) {
						cache = {
							coords : {
								"latitude": google.loader.ClientLocation.latitude, 
								"longitude": google.loader.ClientLocation.longitude
							}
						};
					}
					callback(cache);
				}
			}
		};

		head.insertBefore( script, head.firstChild );
	};

	geolocation.watchPosition = geolocation.getCurrentPosition;

})(navigator.geolocation);




// usage
navigator.geolocation.watchPosition(function(pos){
  console.log("I'm located at ",pos.coords.latitude,' and ',pos.coords.longitude);
});