Develop Reference

How to run to if statements simultaneously in javascript?

I am developing an employee login system that calculates the total time employee was logged in including the break times etc so I have two components 1. which keeps calculating the time until the employee is logged in 2. which calculates the total time of break. So in this situtation I do not want the login time to stop when the break is punched instead I want that break and login time should be running together
const [isLoggedIn, setLoggedIn] = useState(true)
const [isBreakPunched, setBreakPunch] = useState(true)
const [breakTime, setBreakTime] = useState(0);
const [loginTime, setLoginTime] = useState(0);
useEffect(() => {
if (isLoggedIn) {
const interval = setInterval(() => {
setLoginTime(onlineTime + 1);
}, 1000);
return () => clearInterval(interval);
}
if (isBreakPunched){
const interval = setInterval(() =>{
setBreakTime(auxTime +1);
},1000);
return ()=> clearInterval(interval);
}
});
When this runs, the loginTime is only running because the first condition is for login time indeed so to run the breakTime I have to stop the loginTime. This code is treating both as if..else.. loop
My query is that I want to run these both simultaneously when condition is true of anyone, they should be independent from each other

setInterval( () => {
if (isLoggedIn) {
setLoginTime(onlineTime + 1);
}
if (isBreakPunched) {
setBreakTime(auxTime +1);
}
}, 1000);
This interval checks if someone is logged in to set the login time, and sets the break time if they are on a break. BTW, it doesn't make sense that you want the login times and break times to be set depending on each other's condition while being 'independent' of each other.

Tone JS - Transport.stop(); does not work with scheduled events

I am using Tone JS for a project and I am using Transport.scheduleOnce to schedule events with the Sampler. Here is what I have so far, also here is a fiddle of it (you may need to click run a couple times to hear the audio come through when fiddle initially loads)
My code:
const sound = 'https://archive.org/download/testmp3testfile/mpthreetest.mp3';
let samplerBuffer;
const sampler = new Promise((resolve, reject) => {
samplerBuffer = new Tone.Sampler(
{
A1: sound
},
{
onload: () => {
resolve()
}}
).toMaster();
})
sampler.then(() => {
Tone.Transport.scheduleOnce(() => {
samplerBuffer.triggerAttack(`A1`, `0:0`)
});
Tone.Transport.start();
setTimeout(() => {
console.log('Now should be stopping');
Tone.Transport.stop();
},1000)
})
I am trying to stop the audio from playing after 1 second using the Transport.stop() method however it does not seem to work. I think I have followed the docs as I should so where am I going wrong?

Tone.Transport is triggering your sample.
What you want to do is either use the Tone.Player if you only want to play sounds like a "jukebox".
If you really need a sampler, then should to look into Envelopes because the Sampler uses one.
In short: The Tone.Transport like the maestro in a concert. Transport is only setting the time (only the BPM not the playback speed). Tone.Transport.start() will trigger all registered instruments (in your case the Sampler) to start doing whatever you programmed them to do. If you want to stop the Sampler from playing in this mode. You can do samplerBuffer.releaseAll()
const sound = 'https://archive.org/download/testmp3testfile/mpthreetest.mp3';
let samplerBuffer;
const sampler = new Promise((resolve, reject) => {
samplerBuffer = new Tone.Sampler(
{
A1: sound
},
{
onload: () => {
resolve()
}}
).toMaster();
})
sampler.then(() => {
Tone.Transport.scheduleOnce(() => {
samplerBuffer.triggerAttack(`A1`, `0:0`)
});
Tone.Transport.start();
setTimeout(function() {
console.log('Now should be stopping');
samplerBuffer.releaseAll();
// samplerBuffer.disconnect();
},1000)
})
https://jsfiddle.net/9zns7jym/6/

Nodejs function running every 2 minutes lost over time

This is quite hard problem to describe.
I have a koajs app with a function which is created in multiple instances (10-1000 range) every 2 minutes. this scheduled job created on app startup. I use koajs because i need a few simple api endpoints for this app. It is running well for first 3-5 hours and then the count of created instances starts to decrease and some of the log output disappears.
Here is the minimal sample based on actual code:
server.ts
const bootstrap = async () => {
process.setMaxListeners(0); //(node:7310) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 uncaughtException listeners added to [process]. Use emitter.setMaxListeners() to increase limit
//appears on app startup (however seems like this setMaxListeners(0) doesnt affect anything since the warning persist)
const app = new Koa();
app.use(async ctx => {
ctx.body = "Welcome to my Server!";
});
app.listen(port);
new Main().run();
};
bootstrap();
main.ts (tried: cron npm package, node-scheduler, setInterval, recursive setTimeout) to run the scheduledJobWrapper.
isStarting: boolean = false;
async run() {
logger.info(`running the app, every 2 minutes`);
//let that = this;
// new CronJob(`*/2 * * * *`, function () {
// that.scheduledJobWrapper();
// }, null, true, 'America/Los_Angeles');
const interval = 2 * 60 * 1000;
setInterval(() => {
this.scheduledJobWrapper();
}, interval);
}
async scheduledJobWrapper() {
logger.info("here scheduledJobWrapper");
let args = {};
//some irrelevant logic to set the arguments
await this.scheduledJob(args);
}
async scheduledJob(args) {
try {
logger.info("starting");
if (!this.isStarting) {
this.isStarting = true;
const runningCount = Executor.tasks.length; //Executor.tasks is a singleton containing some info about tasks. details are irrelevant. the point is it contains the active tasks.
const tasksLimit = 100;
if (runningCount < tasksLimit) {
for await (const i of Array(tasksLimit - runningCount).keys()) {
if (Executor.tasks.length > 20)
await global.sleep(5 * 1000);
this.startWrapper(args); //calling main task here
}
}
this.isStarting = false;
logger.info(`Started: ${Executor.tasks.length - runningCount}`);
}
} catch (e) {
logger.error("Error running scheduled job: " + e.toString());
}
}
In this example the problem manifests as following:
All work as expected first 3-5 hours, later for each time the scheduled function called:
logger.info("here scheduledJobWrapper"); does now show any output.
logger.info("starting"); not in the output
this.startWrapper does run and the code inside it is being executed.
Despite that the code inside of this.startWrapper is still running, the count of newly created jobs is slowly decreasing.
Hardware (RAM/CPU) is not getting any significant load (CPU under 10%, RAM under 20%)
Any clue on possible reason?
nodejs: 12.6.0
Thanks!
UPDATE
it seems like that with the usage of setInterval the app is running OK for a longer time (6-24 hours), but after that the problem still starts.

The issue is with setInterval function. It gets slow down with the time. It has wierd behavior too. You can create custom setInterval using setTimeout or use third-party module and give try.
Sample setInterval Implementation.
const intervals = new Map();
function setInterval(fn, time, context, ...args) {
const id = new Date().getTime() + "" + Math.floor(Math.random() * 10000);
intervals.set(
id,
setTimeout(function next() {
intervals.set(id, setTimeout(next, time));
fn.apply(context, args);
}, time)
);
return id;
}
function clearInterval(id) {
clearTimeout(intervals.get(id));
}
setInterval(console.log, 100, console, "hi");
You can also enhance, by adding delta time loss in next setTimeout.
Meaning if time loss, run next setTimeout earlier.

First of all, It will be better to move instance of Main() in listen scope:
app.listen(port, () => {
new Main().run();
});
I don't know how good idea is to run setInterval function in the backend side. It's better to extract this logic and move it in cron job.
Are we sure that the machine can run 100 tasks? Please count the tasks by order and see when the problem starts. Probably you can not schedule 100 tasks and exists one limit somewhere

jQuery prevent reload if button clicked

I have a jQuery datatable that immediately loads ON READY. After that, the datatable is reloaded every 30 seconds. This feature is functioning properly.
I have added a search feature that automatically reloads the datatable with new search results. This part is also functioning properly.
The problem I am experiencing is when I am using the search feature, and the new search results are returned. After 30 seconds, the new results are cleared and the datatable reloads with all of the original records.
Here is what I am currently attempting:
$(document).ready(function()
{
var searchCriteria = "";
displayBookings(searchCriteria);
var idle = 0;
var idleInterval = setInterval(timer, 30000);
$(this).mousemove(function(e){idle = 0;});
$(this).keypress(function(e){idle = 0;});
function timer()
{
idle = idle + 1;
if(idle > 2)
{
displayBookings(searchCriteria);
console.log('table reloaded');
}
}
$('#searchPending').on('click', function()
{
var isPending = 'Y';
var searchCriteria = {
isPending: isPending
};
displayBookings(searchCriteria);
});
});
The function displayBookings() takes searchCriteria. If searchCriteria is blank, then a basic query is fired. Obviously is searchCriteria contains parameters, then the same query is fired with a WHERE clause attached. I did not disclose the code for displayBookings().
All I need to do is stop the 30 second interval if the #searchPending button is clicked.

Clear the interval so it will stop loading.
clearInterval(idleInterval)
specifically in your code:
$('#searchPending').on('click', function()
{
clearInterval(idleInterval)
var isPending = 'Y';
var searchCriteria = {
isPending: isPending
};
displayBookings(searchCriteria);
});

Rather than start and stop the timer interval, since you'll run into a bit of a race condition, you can just have the "refresh" (your "timer" function) refresh using the latest search criteria. To do this, just pass the same object into your displayBookings function. E.g.
const search = { criteria: "" };
$(...).click(() => {
search.criteria = 'change it...';
displayBookings(search.criteria);
});
setInterval(() => displayBookings(search.criteria), 30000);
This way, if a refresh happens, it will use the latest search.criteria. You can achieve the same result with minimal change in your code by simply removing the var from the second searchCriteria. Currently, without removing the var, your outer criteria is being "shadowed" by your inner.
I alluded to debouncing1 in one of my comments. I misread the code and debouncing is not what you want. Instead, you want to only "refresh" if there hasn't been any user activity within some threshold. Here's an alternative from the approach you used:
let lastInteraction = 0;
function interact() {
lastInteraction = Date.now();
}
$(this).mousemove(interact);
$(this).keypress(interact);
Then in your refresh function:
if (Date.now() - lastInteraction > threshold) { ...
Implementing both the central criteria and revised idle check:
$(document).ready(function() {
const idle = {
threshold: 1000,
lastInteraction: 0,
interact() {
idle.lastInteraction = Date.now();
},
isIdle() {
return Date.now() - idle.lastInteraction > idle.threshold;
}
};
const search = { criteria: "" };
$(this).mousemove(idle.interact);
$(this).keypress(idle.interact);
setInterval(() => {
if (idle.isIdle()) {
displayBookings(search.criteria);
}
}, 30000);
$('#searchPending').on('click', () => {
search.criteria = { isPending: 'Y' };
displayBookings(search.criteria);
});
displayBookings(search.criteria);
});
1 The Wikipedia article linked to discusses debouncing with a keyboard. It's the same concept. You'd use debouncing on your displayBookings function if you plan on having it execute live as the user is typing. This would prevent too many HTTP requests from happening in a short duration of time.

Simplest possible irrevocable timout / cooldown function?

I'm trying to add a 1 second cooldown to my send-message system (as in, you can send 1 message per second max). So my initial thought was simply to create a timeout, and before attempting in sending to check if it exists still. That turned out to take more line of code than I anticipated initially.
Is there something I'm missing here? Isn't there something as simple as:
//inside some message sending function
if(!mySuperCooldown)
{
//send message
mySuperCooldown = cooldown(1000);
}
Everything else I construct successfully ends up taking loads of lines, and it appears to me as something someone thought of before. Thank you, and excuse my illiteracy.

Have a flag that allows messages, and set it to false when a message is sent. Then set a timeout for 1000 milliseconds that resets the flag to true.
var allowMessage = true;
function sendMessage(msg) {
if (allowMessage) {
//do something
allowMessage = false;
setTimeout(() => allowMessage = true, 1000);
}
}

Make a higher order function that turns a normal function into one that is rate limited:
function rate_limit(delay, func) {
var last_call = null;
return function() {
if (last_call && (Date.now() - last_call <= delay)) {
return;
}
last_call = Date.now();
return func();
};
}
You can then rate limit any function:
var my_function = rate_limit(1000, function() {
console.log('foo');
});
Running my_function() will only call your original function once per second.