I'm working on a Geolocation tool for a mobile website and so far i got this:
The Geolocation verification from here:
if (navigator.geolocation) {
navigator.geolocation.getCurrentPosition(successFunction, errorFunction);
} else {
console.log('Geolocation not enabled in your browser.');
}
The toRad() function from Caspar's answer here:
if (typeof(Number.prototype.toRad) === "undefined") {
Number.prototype.toRad = function() {
return this * Math.PI / 180;
}
}
and the successFunction() from the first link, Movable Type Scripts and some others modifications:
function successFunction(position) {
var lat1 = position.coords.latitude;
var lon1 = position.coords.longitude;
function calcdist(nLoja,nLat,nLong) {
this.loja = nLoja;
this.lat = nLat;
this.long = nLong;
}
aLocal = new Array(3)
aLocal[0] = new calcdist("leblon",-22.982279,-43.217792);
aLocal[1] = new calcdist("ipanema",-22.98376,-43.212138);
aLocal[2] = new calcdist("barra",-22.999118,-43.357867);
var i = 0;
//for (var i = 0; i < 4; i++){
lat2 = aLocal[i].lat;
lon2 = aLocal[i].long;
var R = 6371;
var dLat = (lat2-lat1).toRad();
var dLon = (lon2-lon1).toRad();
var lat1 = lat1.toRad();
var lat2 = lat2.toRad();
var a = Math.sin(dLat/2) * Math.sin(dLat/2) +
Math.sin(dLon/2) * Math.sin(dLon/2) * Math.cos(lat1) * Math.cos(lat2);
var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
var d = R * c;
var thediv = document.getElementById('locationinfo');
thediv.innerHTML = '<p>Distance user-' + aLocal[i].loja + ': ' + d + '</p>';
//}
}
This works just fine on my desktop and my iphone. The problem comes when i comment the i=0;
line and uncomment the for()
statement right after (as well as the closing bracket). Chrome's console returns me an error:
Uncaught TypeError: Cannot read property 'lat' of undefined
For this line:
lat2 = aLocal[i].lat;
The reason for the loop is that i want to do the math x times to check which shop is closer to the user (by getting the smallest distance between user and each shop). But i can't seem to find out why it won't allow the loop.
Thanks a lot in advance.
Your loop condition is
i<4
soi
will be0, 1, 2, 3
, but you only have array indices0, 1, 2
You can't go past the length of the array, so change the loop condition to go until the length of the array using
i < aLocal.length
aLocal
has three elements. Your loop goes from 0 to 3 so that are 4 elements.