Get GPS data

// --------------------------
// install:
// npm install exif

var ExifImage = require('exif').ExifImage;
var fs = require('fs');

isEmpty = function(obj) {
    return Object.keys(obj).length === 0;
}

exif_get_gpsdata = function(exif )
{
    var gps = exif.gps;
    if ( isEmpty(gps) ) {
        return null;
    }

    var lat = gps.GPSLatitude   || null;
    var lon = gps.GPSLongitude  || null;

    if (!lat || !lon) {
        return null;
    }

    //Convert coordinates to WGS84 decimal
    var latRef = gps.GPSLatitudeRef || "N";
    var lonRef = gps.GPSLongitudeRef || "W";

    lat = (lat[0] + lat[1]/60 + lat[2]/3600) * (latRef == "N" ? 1 : -1);
    lon = (lon[0] + lon[1]/60 + lon[2]/3600) * (lonRef == "W" ? -1 : 1);

    var imgDir = gps.GPSImgDirection || NaN;

    var altRef = gps.GPSAltitudeRef || NaN;

    var alt = gps.GPSAltitude || 0;
    var alt = gps.GPSAltitude * (altRef == 0 ? 1 : -1);

    return {
        'lat' : lat.toFixed(6),
        'lon' : lon.toFixed(6),
        'alt' : alt.toFixed(1),
        'dir' : imgDir.toFixed(3)
    }
}


// --------------------------
if (process.argv.length <= 2) {
    console.log("Usage: " + __filename + " path/to/directory");
    process.exit(-1);
}
var path = process.argv[2];

var files_list = fs.readdirSync(path);

var total_files = 0;
var valid_files = 0;

files_list.map(function (fn) {
    var filename = path + '\\' + fn;

    total_files++;
    new ExifImage({ image : filename }, function (error, exifData) {

        if (!error) {
            var data = exif_get_gpsdata( exifData );
            if (data) {
                valid_files++;
                console.log(filename + ' -> Lat: '+data.lat+', Lon: '+data.lon+', Alt: '+data.alt+', Dir: '+data.dir );
            }
        }
    });
})
console.log();
console.log('Total files: ' , total_files);
console.log('Valid files: ', valid_files);