How to access global variables and modify their state

[boris runakov]

Hello !
What is the best cleanest way to access global variables / or variables with state in general ? Currently I am trying with global.get/set methods but the code gets convoluted.
For example a simple countdown I have wrote in js , and tried to implement it in a function node gets something like this :

var timer = flow.get('timer') || {
    "running": false,
    "startTime": 0,
    "endTime": 0,
    "ms": 0,
    "sec": 0,
    "min": 0,
    "shift": 0
}
var time = flow.get('time') || 0;

if (msg.topic == "timer_status") {
    node.warn({
        payload: timer
    });
}
if (msg.topic == "start") {
    node.warn({
        payload: "start pressed"
    });

    start();
}
if (msg.topic == "stop") {
    node.warn({
        payload: "stop pressed"
    });

    stop();
}
if (msg.topic == "value") {

    flow.set('time', msg.payload);
    node.warn({
        payload: flow.get('time')
    })
}

function start() {
    var timer = flow.get('timer');
    timer.running = true;
    flow.set('timer', timer);

    configTimer();

    node.warn({
        payload: timer
    })
}

function stop() {
    var timer = flow.get('timer');
    timer.running = false;
    flow.set('timer', timer);
    node.warn({
        payload: timer
    });
}

function configTimer() {
    var timer = flow.get('timer');
    timer.startTime = Date.now();
    flow.set('timer', timer)
    if (timer.running) {
        checkTime();
    }
}

function checkTime() {
    var timer = flow.get('timer');

    if (timer.running) {
        var seconds = 0,
            minutes = time,
            hours = 0,
            remaining = 0,
            shift = timer.shift;

        timer.endTime = (seconds * 1000) + (minutes * 60 * 1000) + (hours * 60 * 60 * 1000) + shift;

        if (timer.startTime + timer.endTime >= Date.now()) {

            timer.ms = timer.startTime + timer.endTime - Date.now();
            timer.min = (timer.ms / 1000 / 60) << 0,
            timer.sec = (timer.ms / 1000) % 60 << 0;
            remaining = timer.min + ':' + timer.sec;

            node.send({
                time: remaining
            });

            setTimeout(checkTime, 1000);
        } else {
            stop();
        }
        flow.set('timer', timer);
    }
}

Is there a way I can define timer and time variables in a different node and access/modify them directly without using get/set methods like in the code above ?
Thank you in advance

[Nicholas O'Leary]

You have two choices.

You either pass data in the messages going between nodes or you use flow/global context as you are doing.

The context objects are there specifically to enable state to be shared between nodes.

Nick

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[boris runakov]

Can you give me an example on how I could change an object property by passing data in the messages ?

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[Nicholas O'Leary]

> Can you give me an example on how I could change an object property by passing data in the messages ?

Sorry, I was answering a slightly different question - how to share state between nodes. An alternative to using the context objects is, for some uses, to just pass data between nodes using the messages flowing between them. But that isn't appropriate in many cases - which is why the context objects exist.

To answer you specific question:

> What is the best cleanest way to access global variables / or variables with state in general ?

The get/set functions are the way you access the flow/global context.

Nick

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[boris runakov]

So I suppose I can omit the flow.get() in every function I am using , since I declare the timer and time variables on top of the function node.
Also is there an option to instantiate nodes on deploy or restart of nodered?
Appreciate your feedback !