var io = require('socket.io').listen(3000); io.sockets.on('connection', function (socket) { console.log("New connection!"); socket.on('test', function (data,ack) { console.log(data); var testObject = {"testKey" : "testValue", "testArray": ["value1", "value2", "value3"], "testDic": {"key1":"value1","key2":"value2"}, "testMix":["one",{"twoDic":[1,2,"2",2.0,2.1]}],"specialKey":"Ñoña-2_3"}; ack(testObject); console.log("I acked"); }); });