How to play back time-related events - node.js

Question

To get familiar with Node.js I'm working on a little project where users can play a piano in their browser and all connected users get to hear the keys played. For this I'm using Express with Socket.io.
So far so good: communication works and sounds are heard by all users. My next challenge is to let a user record him playing the piano and then play it back to all connected users.
The recording itself is rather straightforward:
user.socket.on('keyDown', function (message) {
user.socket.broadcast.emit('keyDownReceived', JSON.stringify(message));
if (user.isRecording) {
var key = message.key;
var time = currentTime() - user.recordingStartTime;
user.recording.timeOffsets.push(time);
user.recording.keys.push(key);
}
});
Every time a key is pressed, I fill two arrays. One with the time offsets for each key since the record button was pressed and one with the key. This later gets saved to MongoDB.
My question is how I would go about playing this back to the user. My initial idea was to do the following:
user.socket.on('playRecording', function () {
user.playRecordingStartTime = currentTime();
var interval = setInterval(function () {
var time = currentTime() - user.playRecordingStartTime;
var index = user.recording.timeOffsets.indexOf(time);
if (index != -1) {
var message = {key: user.recording.keys[index]};
user.socket.broadcast.emit('keyDownReceived', JSON.stringify(message));
}
}, 1);
});
So essentially I'm firing a timer every millisecond and doing a reverse lookup in the array to see if a key has been pressed at that time. As you might imagine, this is not ideal and often times keys are skipped because the execution takes too long.
How should such a problem be tackled in Node.js?
Edit: As suggested by Steven, I could just use setTimeout. How embarrassing
user.socket.on('playRecording', function () {
user.recording.timeOffsets.forEach(function (offset, index) {
setTimeout(function () {
var message = {key: user.recording.keys[index]};
user.socket.emit('playKey', JSON.stringify(message));
user.socket.broadcast.emit('keyDownReceived', JSON.stringify(message));
}, offset);
});
});

Answer 1

In your specific case I would recommend looping over the notearray you are playing and creating a new setTimeOut() with each time interval of the including note.
As an example:
var arrNotes = [{ note: "do", time: 1500 }, { note: "re", time: 2500 }],
length = arrNotes.length,
i = 0;
for (var i = 0; i < length; i++){
(function () {
var t = i;
setTimeout(function () {
playNote(arrNotes[t].note);
}, arrNotes[t].time);
})();
}
function playNote(note) {
console.log(note);
}