1.js

// -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
// Geo Hash
// -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
function geohash( coord, resolution ) {
    var rez = Math.pow( 10, resolution || 0 );
    return Math.floor(coord * rez) / rez;
}

2.js

// Create Proximity Channel
channel = geohash( pos.latitude, 0 ) + '' + geohash( pos.longitude, 0 );

3.js

// Connect to Proximity Channel
pubnub.subscribe({
     channel : channel,
     message : receive,
     connect : ready,
    presence : presence
});