clearInterval on "OFF" payload

Question

I am having newbie difficulties implementing clearInterval with a certain payload. The

if(msg.payload.state === "OFF")

works, but the timer doesn't stop.

Amongst many resources, I have seen how to stop setInterval in JS in node-red..?, node.js: how to use setInterval and clearInterval?, clearInterval doesn't clearInterval & clearInterval On Image Slider Plugin

I did have a similar function, "dominos" that I used to make sure I was parsing the "OFF" payload. I have included a lot of commented code to show what I had tried. Sorry about the mess!

Is it an issue with my syntax?

Is the code logical?

var input = msg.payload.state;
let timer = 0;

var red = {"state":"ON","brightness":255,"color":{"r":255,"g":0,"b":0}};
var green = {"state":"ON","brightness":255,"color":{"r":0,"g":255,"b":0}};


function xmas() {    // REPEATS!
    node.send({payload:red});
    setTimeout(function(){
        node.send({payload:green});
    }, 1500);
}
// repeat with 3 second interval
timer = setInterval(() => xmas(), 3000);
if (msg.payload.state === "OFF") {
    timer = clearInterval();
}

Answer 1

The important thing to remember about a function node is that it's state is totally reset for each incoming message. This means that timer will ALWAYS be reset to zero by the let timer = 0;

If you want to store any state between messages then you need to use the context.

Also the way you are using clearInterval() will never work, you need to pass the reference to the timer object to this function for it to do anything useful.

The following function node should do what I think you intended.

var red = {"state":"ON","brightness":255,"color":{"r":255,"g":0,"b":0}};
var green = {"state":"ON","brightness":255,"color":{"r":0,"g":255,"b":0}};


if (msg.payload.state != "OFF") {
   var timer = setInteval(()=>{
      node.send({payload: red});
      setTimeout(() => {
           node.send({payload: green});
      }, 1500);
   }, 3000);
   context.set("timer",timer);
} else {
   var timer = context.get("timer");
   clearInterval(timer);
}