Stopwatch on node-red?

I want to make a stopwatch for some condition in my project.
for ex. if my node get data(something like "START") from mqtt so that will make a time count too, time will count untill my node get an another data(like "STOP") and I'll record that time between start and stop (ex. 01:32:24 ).
Thank you.

Well, one way of doing this is when you send the "Start" and "Stop" signals, you include a time stamp with them.

Then you simply subtract them.

Rather than sending ONLY a "message", send it with a TOPIC which will be used to determine if it Stops or Starts.

(Two buttons)
Both inject the "time stamp" - which is the default in the inject node.
Set the topic for on as START and the topic for the other as STOP.

Use a function node.
Something like:

let difference = 0;
let start = 0;
if (msg.topic == "START")
if (msg.topic == "STOP")
    start = context.get("START");
    difference = msg.payload - start;
    msg.payload = difference
return msg;

Something LIKE that.

I'm not a coder, and I may have made a mistake in there, but I hope you can see the concept of what I am meaning.

Then send that node to another node (who's name I can't remember) to format it into a time format.


Thank you for reply me. :grinning:
I'll try your suggestion and I have few question but let me try this first.