Executing some function when the state of a variable changes?

Question

i am trying to make a function in my app that is supposed to update the status of my hue lamps when the states of one of them changed.

For now, i have done this :

async.waterfall([
function getLightsId(callback) {
    args = {
        path: {
            "username": "webjeremie"
        }
    };

    client.registerMethod("getLightState", "http://hue.jeremieledieu.fr/api/${username}/lights/", "GET");

    client.methods.getLightState(args, function (data, response) {
        var ids = [];
        for (key in data) {
            ids.push(key);
        }
        callback(null, ids);
    });
},
function getLightsState(ids, callback) {
    var lightsState = new Object();
    async.reduce(ids, {}, function(lightsState, id, rcallback) {
      getLightState(id, function(state) {
        lightsState[id] = state;
        rcallback(null, lightsState);
        });
    }, callback);
},


], function (err, currentState) {

        io.sockets.on('connection', function (socket) {
            socket.emit('updateLightsState', currentState);
            previousState = currentState;
        });
});

This get me the states of all the lamps in the currenState but im stuck at how should i constantly compare the previous state with the current state, and only emit when the currentState != previousState

Any ideas ?

score 0 · Accepted Answer · answered Apr 05 '14 at 13:37

0

I can give you a suggestion.

Set a value to a variable.

var origVal = "Original";
var yourVariable = "Original";

setInterval(function(){
   if(yourVariable !== origVal){
     // do something.
   }
},1000)

answered Apr 05 '14 at 13:37

Amit Joki

58,320
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Thanks, it was as simple as this :) – Jeremie4zw Apr 05 '14 at 14:45

score 0 · Answer 2 · edited May 23 '17 at 11:49

0

Take a look at answer #1180790

I think, object.watch will make the work here.

edited May 23 '17 at 11:49

Community

1
1

answered Apr 05 '14 at 13:46

At linked answer, you can find linked Eli Grey`s [implementation](https://gist.github.com/eligrey/384583) to work on all major browsers. – Apr 05 '14 at 14:36

Executing some function when the state of a variable changes?

2 Answers2