Count down function

[koos147]

Good day,

I expect that i made a realy simple mistake.

The idea is that when a message arrive the output count down.

var i = 10;
while (i >= 5) {
msg.payload=i;
node.send(msg);
  i--;
}

Expected output

10
9
8
7
6
5

However the number of outputs is correct. but the payload is wrong.

10
5
5
5
5
5

What do i do wrong?

[JGKK]

Try a for function.

for(i=10;i>4;i--){
    node.send({payload:i});
}
node.done();
return;

Johannes

[JGKK]

actually i don’t see anything wrong with the while loop either as it works for me:

let i = 10;
while(i >= 5){
    msg.payload = i;
    node.send(msg);
    i--;
}
node.done();
return;

[Steve-Mcl]

My guess is the op is using node-red pre version 1

Message is getting overwritten in the loop before debug output.

In later version, message is cloned by default to handle the new asynchronous nature of version 1

Cloning messages in a flow

[Trying_to_learn]

I think you are missing the whole context part.

The variable i is not honoured between messages.

So the code would have to look (something) like:

if (context.get("counter) > 0
{
     let i = context.get("counter");
} else
{
    context.set("counter",10);
}
while (i > 5)
{
    msg.payload = 1;
    i = i - 1;
    context.set("counter",1);
    return msg;
}

[JGKK]

This doesn’t work what your proposing. The first part will will only get executed when a new message arrives and the while loop will only go once because you return out of it.
He needs to use the node.send() function as sending messages from a loop is asynchronous work.
This will count down one by only when new messages arrive and the while loop has no function at all in your variant.

[Trying_to_learn]

Yeah, ok.

I am just now learning about this asynchronous stuff and reading about node.send( ).

Sorry for the incorrect reply.

I am going to have to read up on what this new thing is. Though it has been around since NR 1.x onwards.

And I think I also didn't quite get what was meant anyway.

[Paul-Reed]

Another offering!
This time with a optional delay built into the countdown.

[{"id":"fbf79e8f.4b4f9","type":"function","z":"4487e413.bb781c","name":"Countdown","func":"var counter = 10;\n\nvar countdown = setInterval(function(){\n  node.send({\"payload\":(counter)});\n  counter--;\n\n  if (counter <5) {\n    clearInterval(countdown);\n  }\n}, 1000);","outputs":1,"noerr":0,"x":380,"y":990,"wires":[["773a223c.2189ac"]],"icon":"font-awesome/fa-hourglass-1"},{"id":"3a80d1cb.a423de","type":"inject","z":"4487e413.bb781c","name":"","topic":"","payload":"","payloadType":"str","repeat":"","crontab":"","once":false,"onceDelay":"","x":210,"y":990,"wires":[["fbf79e8f.4b4f9"]],"icon":"node-red/arrow-in.svg"},{"id":"773a223c.2189ac","type":"debug","z":"4487e413.bb781c","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":560,"y":990,"wires":[]}]

Edit// flow updated

[koos147]

Good day all,

Thank you all for the effort.

the version installed is 0.15.2 (i think i need to do some updating )
I tested the version of Paul-Reed and that does exactly what i need.

the current version is 5 nodes and i can finaly replace them.

Again many thanks for your quick help.