RIA

Geo Location

Finding Location

• modern devices can get location coordinates

• phones and tablets can use GPS• desktops and laptops

–often cannot use GPS –can get the location of the ISP–not as accurate but better than nothing

Using DOM to Find Location

navigator.geolocation.getCurrentPosition– asynchronous method that uses callbacks– getCurrentPosition(locFound, locError)– locFound is called if it is successful– locError is called if it is not successful

handle errors if location is not supported

Example

if (navigator.geolocation) {navigator.geolocation.getCurrentPosition(locOK,locErr);

} else {document.getElementById("loc").innerHTML=

"GEO location is NOT supported";}function locOK(currPos){

document.getElementById("lat").innerHTML="Latitude="+currPos.coords.latitude;

document.getElementById("lng").innerHTML="Longitude="+currPos.coords.longitude;

}function locErr(e){

document.getElementById("loc").innerHTML="Error getting current location: "+e.message;

}

Using Google Map API

assign the source of an img tag to the Google URL for making a map

just a static image so it does not allow for interaction

example:var latlon = position.coords.latitude + "," + position.coords.longitude;var img_url = "http://maps.googleapis.com/maps/api/staticmap?center="+latlon+"&zoom=14&size=400x300&sensor=false";document.getElementById("mapholder").innerHTML = "<img src='"+img_url+"'>";

Distance Calculation

there are sites that can help with calculating the distance between two points using latitude and longitude

for example: http://www.movable-type.co.uk/scripts/latlong.html

you may need to adjust the units (km vs meters)

Sorting Arrays of Objects

create a compare function like:function compare(x,y){ if(x.id < y.id) return -1; if(x.id > y.id) return 1; return 0;}

then in your code you can use:objs.sort(compare);

as long as each object in objs has an id field