Develop Reference

Intermittent failure in nodeJS timer function

I am not familiar with this function, however I am seeing intermittent failures, sometimes the timer function will execute and the newState variable switches, sometimes it doesn't. Please can you check my understanding of what this is doing?
function motionHandler() {
console.log('im in motionhandler func')
var newState = true;
changeAction(newState);
if(this.timer !== undefined) clearTimeout(this.timer);
this.timer = setTimeout(function(){changeAction(!newState);}, this.window_seconds * 1000);
};
From what I understand, when this function executes I set the newState variable to true. I then execute changeAction which sets my motion detector to "true" (motion detected).
I then create a timer. If this.timer has something in it, then clear. I then create a timeout which will countdown from window_seconds * 1000 (ie. 5x1000 milliseconds = 5 seconds). Once that timeout is reached, I will execute the changeAction function and set newState to the opposite of what it currently is?
Assuming all of that is correct, sometimes newState gets reset, other times it doesn't.
I am executing the motionHandler function every time I receive a particular RF code from a transmitter. The timeout is there to reset the motion detector back to false when no codes are received.
The full code is actually a plugin for home bridge, and can be seen here:
https://github.com/mattnewham/homebridge-RFReceiver/blob/master/index.js
This is my first real foray into Javascript/NodeJS so I don't really know how to troubleshoot this (other than my console.logs!)
Full code:
var Service;
var Characteristic;
var rpi433 = require("rpi-433"),
rfSniffer = rpi433.sniffer({
pin: 2, //Snif on GPIO 2 (or Physical PIN 13)
debounceDelay: 1000 //Wait 500ms before reading another code
}),
rfEmitter = rpi433.emitter({
pin: 0, //Send through GPIO 0 (or Physical PIN 11)
pulseLength: 350 //Send the code with a 350 pulse length
});
var debug = require("debug")("RFReceiverAccessory");
var crypto = require("crypto");
module.exports = function(homebridge) {
Service = homebridge.hap.Service;
Characteristic = homebridge.hap.Characteristic;
homebridge.registerAccessory("homebridge-RFReceiver", "RFReceiver", RFReceiverAccessory);
}
function RFReceiverAccessory(log, config) {
this.log = log;
// url info
this.name = config["name"];
this.rfcode = config["rfcode"] || 4;
this.window_seconds = config["window_seconds"] || 5;
this.sensor_type = config["sensor_type"] || "m";
this.inverse = config["inverse"] || false;
}
RFReceiverAccessory.prototype = {
getServices: function() {
// you can OPTIONALLY create an information service if you wish to override
// the default values for things like serial number, model, etc.
var informationService = new Service.AccessoryInformation();
informationService
.setCharacteristic(Characteristic.Name, this.name)
.setCharacteristic(Characteristic.Manufacturer, "Homebridge")
.setCharacteristic(Characteristic.Model, "RF Receiver")
.setCharacteristic(Characteristic.SerialNumber, "12345");
var service, changeAction;
if(this.sensor_type === "c"){
service = new Service.ContactSensor();
changeAction = function(newState){
service.getCharacteristic(Characteristic.ContactSensorState)
.setValue(newState ? Characteristic.ContactSensorState.CONTACT_DETECTED : Characteristic.ContactSensorState.CONTACT_NOT_DETECTED);
};
} else {
service = new Service.MotionSensor();
changeAction = function(newState){
console.log('changing state');
service.getCharacteristic(Characteristic.MotionDetected)
.setValue(newState);
};
}
function motionHandler() {
console.log('im in motionhandler func')
var newState = true;
changeAction(newState);
if(this.timer !== undefined) clearTimeout(this.timer);
this.timer = setTimeout(function(){changeAction(!newState);}, this.window_seconds * 1000);
};
var code = this.rfcode
var name = this.name
rfSniffer.on('data', function (data) {
console.log('Code received: '+data.code+' pulse length : '+data.pulseLength);
console.log(code);
if(data.code == code){
console.log("Motion Detected In" +name);
motionHandler()};
});
return [informationService, service];
}
};

Watch a DOM property

I'm trying to monitor the DOM element on a third-party website. The element is non-existent until a countdown timer reaches, then it is created.
I've had some success playing around with: document.getElementsByClassName('countdown ng-hide').length
when it changes from 0 to 1 I want to effect a function.
How would I do this? I've tried using a Mutation Observer but it won't let me observe a null node.
Thanks!
EDIT: This is what I've got so far.
var timesDone = 0;
var songID = 0;
function clickit(xsongID) {
if(document.getElementsByClassName('lottery-countdown ng-hide').length == 1) {
document.getElementsByClassName('media submission ng-scope')[xsongID].click(); songName = document.getElementsByClassName('media-title submission-name ng-binding')[xsongID].outerHTML; timesDone++; }
}
setInterval(clickit, 29900, songID);

I did this recently by setting up an Interval function like this :
var timesTest = 0;
var checkExists = setInterval(function() {
if ($('.yourClassElement').length) {
// ok element found : do your stuff and clear the Interval...
// stuff...
clearInterval(checkExists);
timesTest = 0;
}
timesTest++;
// I won't let this run more than 5 seconds, so :
if (timesTest*100 > 5000)
clearInterval(checkExists);
}, 100);

setTimeout/Interval called from within $.each method?

I am a little confused, I have read from other places that timeout/interval is the best way to make a function in Javascript run every x seconds. I have to make it so that my function runs every 1 second, as this is a rule for the API I'm using.
My code is as follows:
$.each(match_details_json.result.players, function(index, v){
if (v.account_id == 38440257){ //finds desired playerid
var match_id_2 = matches[i];
hero = v.hero_id;
playerpos = v.player_slot;
var kills = v.kills;
var deaths = v.deaths;
var assists = v.assists;
var kda = ""+kills+"/"+deaths+"/"+assists+"";
console.log(match_id_2, hero, playerpos, result, gamemode, kda);
callback();
console.log(match_id_2, hero, result, gamemode, kda);
h=h+1;
setTimeout(get_match_details(h), 10000);
i=i+1;
}
else{
console.log('Not desired player, skipping...');
}
});
Lots of messy code there. But the important part is setTimeout(get_match_details(h), 10000);
Whether that is correct or not, that's me trying to say "Run this function again in 10 seconds" and to continue that, until the each method is finished. It doesn't work.
If necessary, here is my get_match_details function:
function get_match_details(){
$.ajax({
url: 'php/ApiMatchPull.php',
data: {accountid:'38440257', querytype:'GetMatchDetails', querycondition1:'match_id='+matches[h]},
success: function (data) {
console.log ('Match Details were was pulled successfully');
match_details_json = data;
matchdetailsfill(checkvalidity);
}
});
}
Thank you in advance.

This is precisely what setInterval & clearInterval are for.
So instead of setTimeout, you could use it something like :
var timer = setInterval(function() {
get_match_details(h);
}, 1000); // for every second
And when you want to stop it, use:
clearInterval(timer);

You execute the function get_match_details immedatiately, change your code to
setTimeout( function() {
get_match_details(h)
}, 10000 );
What happens in your code is that you loop through all your players and after 10 seconds as many Ajax calls (get_match_details) will be made at the same time.
If you want to have 10 seconds intervals between each ajax call you have to refactor your approach to something like this:
var l = [1,2,3,4,5];
var c = l.length;
var ix = -1;
ajax = function( n ) {
alert( 'do some ajax with ' + n )
}
call = function() {
if( c > ++ix ) {
ajax( l[ ix ] );
setTimeout( function() { call(); }, 1000 );
}
}
call();

Need to delay javascript execution, but setTimeout is proving problematic

Thank you for taking the time to help me.
I am writing a game where an animated train icon moves along a given path to a destination, pausing at waypoints along the way. This is intended to give the impression of animation.
The game is coded in Facebook Javascript. I need to find a way to make the train icon pause for 1 second before moving on to the next waypoint. I hoped to find a function that would allow me to pause script execution for one second, but nothing like that seems to exist in JS. So I tried setTimeout, but my primary problem with this is twofold:
I need to pass an array into the callback function as an argument, and I can't figure out how to make setTimeout do this.
I finally succeeded in using setTimeout to execute my train animation code for 5 waypoints (I overcame the issue in 1 by using global variables). Unfortunately, it appears that all five calls to setTimeout got queued almost simultaneously, which resulted in waiting one second for the first setTimeout to fire, thenn they all fired at once ruining the illusion of train animation.
I've been battling this problem for six hours straight. It would be wonderful if someone could help me find a solution. Thanks!
Here's the code:
function myEventMoveTrainManual(evt, performErrorCheck) {
if(mutexMoveTrainManual == 'CONTINUE') {
var ajax = new Ajax();
var param = {};
if(evt) {
var cityId = evt.target.getParentNode().getId();
var param = { "city_id": cityId };
}
ajax.responseType = Ajax.JSON;
ajax.ondone = function(data) {
var actionPrompt = document.getElementById('action-prompt');
actionPrompt.setInnerXHTML('<span><div id="action-text">'+
'Train en route to final destination...</div></span>');
for(var i = 0; i < data.length; i++) {
statusFinalDest = data[i]['status_final_dest'];
//pause(1000);
gData = data[i];
setTimeout(function(){drawTrackTimeout()},1000);
if(data[i]['code'] == 'UNLOAD_CARGO' && statusFinalDest == 'ARRIVED') {
unloadCargo();
} else if (data[i]['code'] == 'MOVE_TRAIN_AUTO' || data[i]['code'] == 'TURN_END') {
//moveTrainAuto();
} else {
// handle error
}
mutexMoveTrainManual = 'CONTINUE';
}
}
ajax.post(baseURL + '/turn/move-train-final-dest', param);
}
}
function drawTrackTimeout() {
var trains = [];
trains[0] = gData['train'];
removeTrain(trains);
drawTrack(gData['y1'], gData['x1'], gData['y2'], gData['x2'], '#FF0', trains);
gData = null;
}

Typically this would be done by creating an object (say called myTrain) that has all its own data and methods, then call a myTrain.run mehod that looks to see where the train is. If it's between two stations, it calls itself with setTimeout and say a 50ms delay. When it reaches a station, it calls itself in 1000ms, creating a 1 second pause at the station.
If you queue the setTimeouts all at once, you run the risk of them all being delayed by some other process, then all running at once.
Hey, bit of fun (careful of wrapping). Needed a bit of practice with good 'ole prototype inheritance:
<!-- All the style stuff should be in a rule -->
<div style="position: relative; border: 1px solid blue;">
<div id="redTrain"
style="width:10px;height:10px;background-color:red; position:absolute;top:0px;left:0px;"></div>
</div>
<script type="text/javascript">
// Train constructor
function Train(id) {
this.element = document.getElementById(id);
this.timerId;
}
// Methods
// Trivial getPos function
Train.prototype.getPos = function() {
return this.element.style.left;
}
// Trivial setPos function
Train.prototype.setPos = function(px) {
this.element.style.left = parseInt(px,10) + 'px';
}
// Move it px pixels to the right
Train.prototype.move = function(px) {
this.setPos(px + parseInt(this.getPos(),10));
}
// Recursive function using setTimeout for animation
// Probably should accept a parameter for lag, long lag
// should be a multiple of lag
Train.prototype.run = function() {
// If already running, stop it
// so can interrupt a pause with a start
this.stop();
// Move the train
this.move(5);
// Keep a reference to the train for setTimeout
var train = this;
// Default between each move is 50ms
var lag = 50;
// Pause for 1 second each 100px
if (!(parseInt(this.getPos(),10) % 100)) {
lag = 1000;
}
train.timerId = window.setTimeout( function(){train.run();}, lag);
}
// Start should do a lot more initialising
Train.prototype.start = function() {
this.run();
}
// Stops the train until started again
Train.prototype.stop = function() {
if (this.timerId) {
clearTimeout(this.timerId);
}
}
// Set back to zero
Train.prototype.reset = function() {
this.stop();
this.setPos(0);
}
// Initialise train here
var myTrain = new Train('redTrain');
</script>
<p> </p>
<button onclick="myTrain.start();">Start the train</button>
<button onclick="myTrain.stop();">Stop the train</button>
<button onclick="myTrain.reset();">Reset the train</button>

To pass arguments, this might help you:
setTimeout(function() {
(function(arg1, arg2) {
// you can use arg1 / arg2 here
})('something', 123);
}, 1000);
Or, if you use a defined function:
setTimeout(function() {
someFunction('something', 123);
}, 1000);
It basically starts a timeout; after one second the function is invoked with the specified arguments.

How about using OO principles to simplify the problem? Create an "object" Train which has the following methods:
//train obj
function Train(){
this.isOnWaypoint = function(){
return calculateIsWayPoint()
}
}
//main logic
var train = new Train()
var doneWaiting = false
var doneWaitingTimeout = undefined
var gameLoop = setInterval(1000,function(){
...
if(train.isOnWaypoint() && !doneWaiting){
if(doneWaitingTimeout == undefined){
setTimeOut(5000,function(){
doneWaiting = true
doneWaitingTimeout = undefined
})
}
}
...
})

Here's the solution I finally came up with:
function drawTrackTimeout() {
if(gData != null && gIndex < gData.length) {
var trains = [];
trains[0] = gData[gIndex]['train'];
removeTrain(trains);
drawTrack(gData[gIndex]['y1'], gData[gIndex]['x1'], gData[gIndex]['y2'], gData[gIndex]['x2'], '#FF0', trains);
statusFinalDest = gData[gIndex]['status_final_dest'];
if(statusFinalDest == 'ARRIVED') {
unloadCargo();
} else if (gData[gIndex]['code'] == 'MOVE_TRAIN_AUTO' || gData[gIndex]['code'] == 'TURN_END') {
//moveTrainAuto();
} else {
// handle error
}
gIndex++;
} else {
clearInterval(gIntid);
gIntid = null;
gData = null;
gIndex = 0;
}
}
function myEventMoveTrainManual(evt, performErrorCheck) {
//debugger;
if(mutexMoveTrainManual == 'CONTINUE') {
var ajax = new Ajax();
var param = {};
if(evt) {
var cityId = evt.target.getParentNode().getId();
var param = { "city_id": cityId };
}
ajax.responseType = Ajax.JSON;
ajax.ondone = function(data) {
var actionPrompt = document.getElementById('action-prompt');
actionPrompt.setInnerXHTML('<span><div id="action-text">'+
'Train en route to final destination...</div></span>');
gData = data;
gIndex = 0;
gIntid = setInterval(function(){drawTrackTimeout()},1000);
}
ajax.post(baseURL + '/turn/move-train-final-dest', param);
}
}

Preventing a callback from executing until input stops

A timer to fire an AJAX call if no key is pressed. If a key is pressed, then abort the last timer and add a new timer. That is what I want to do but failed to success. Here is my code:
var t;
input.onkeyup = function(){
$('.confirmText').html('Checking...');
var timeStampObj = new Date()
var timeStamp = timeStampObj.getTime();
var oldTimeStamp = $(this).attr('timeStamp');//I store a timeStamp in the element
if(timeStamp < 500 + oldTimeStamp){
$(this).attr('timeStamp', timeStamp);
clearTimeout(t);
}
t = setTimeout(function(){
$.ajax({
url: 'serverScripts/settings/checkEmailAvailability.php',
data: 'email='+email,
success: function(text){
if(text == 'available'){
$('.confirmText').html('Available!');
}else{
$('.confirmText').html('Occupied!');
}
}
});
}, 500);//Half a second
$(this).attr('timeStamp', timeStamp);
}

It sounds like you're asking for a debouncer. The term comes from electronics. It's a way to prevent multiple events from firing within some time threshold. You can use the following function to create a new function that will only be called if a given amount of time has passed since the last event.
function debounce(callback, timeout, _this) {
var timer;
return function(e) {
var _that = this;
if (timer)
clearTimeout(timer);
timer = setTimeout(function() {
callback.call(_this || _that, e);
}, timeout);
}
}
// requires jQuery
$("div").click(debounce(function() {
console.log("tset");
}, 2000));
The callback given to debounce won't execute as long as click events keep firing.
The excellent Underscore.js library includes an equivalent function and there are at least a couple jQuery plugins:
http://code.google.com/p/jquery-debounce/
http://benalman.com/code/projects/jquery-dotimeout/examples/debouncing/

Where do you define the email variable in your JavaScript?
You need to define email somewhere and then check to see if your script works.
var email = $(this).value; // Pseudo-code - are you using jQuery?