Get specific elements from JSON Object

I would like to know how can I get the JSON objects by position. I'm building an Websocket that will send to the client certain values from time to time, I did this code using Ajax, and I want to follow the same logic:

 $.ajax({
     type: 'GET',
     url: 'locals.json',
     data: {
         get_param: 'locals'
     },
     dataType: 'json',
     success: function(data) {
         $.each(data.locals, function(index, locals) {
             var count = 0;
             setInterval(function() {
                 count++;
                 if (index == count) {
                     console.log(locals.lat);
                 }

             }, 5000);


         });
     }
 });

This code shows me every 5 seconds a different element from my JSON Object, and I would like to follow the same logic on Node.js, but I don't know how to get the index.

I'm using node.js to build my server.

var connection = request.accept('echo-protocol', request.origin);
console.log((new Date()) + ' Connection accepted.');
connection.on('message', function(message) {
    if (message.type === 'utf8') {

        console.log('Received Message: ' + message.utf8Data);
        var fs = require('fs');
        var jsonObj;
        fs.readFile('locations.json', 'utf8', function(err, data) {
            if (err) throw err;
            jsonObj = JSON.parse(data);
            for (var key in jsonObj) {

            }

        });

    } else if (message.type === 'binary') {
        console.log('Received Binary Message of ' + message.binaryData.length + ' bytes');
        connection.sendBytes(message.binaryData);
    }
});

How can I adapt my first code to the second one?

Thank you.

via Rúben Dias