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How can I wait for data change in mongodb database

I've mobile app API in my project.
When payments is done, i need to check powerstatus on mongodb.
PowerStatus changing with post method by another software. I firstly get getpaymentInfo and it has two parameter, paymentInfo and powerStatus. I need to wait until powerStatus be true in some specific time. I am using below codes for this, but I think it is not good. Because loop working in 500 times, and 500 times asking to db.
How can I do this very good to wait until this value return true. But I don't want to interrupt the operations of other functions during this waiting time
var loopCounter = 0;
var getpaymentInfo = await PowerOn.findOne({productSerialNumber: serialNumber});
getpaymentInfo = await PowerOn.findOne({productSerialNumber: serialNumber});
while((getpaymentInfo.powerStatus != true) && (loopCounter < 500) ){
getpaymentInfo = await PowerOn.findOne({productSerialNumber: serialNumber});
if(getpaymentInfo.powerStatus == true)
{
console.log("Wait..",loopCounter)
break;
}
loopCounter++;
}
console.log("after loop powerStatus",getpaymentInfo.powerStatus)

Need Functions That Wait Until Cache Can Be Verified

I'm aware that the immediate response is going to be to use promises for the following problem. However, I've looked at every example I can and nothing seems to be readable to me. Most is done through HTML examples, which I don't understand. Similar posts here have a plethora of arguments on which syntax is appropriate which furthers the confusion. So, please show me how I might use a promise to do the following or if another solution is better.
I'd like for a function to check if the cache is available, and if not, it will reinitialize the cache:
function valData(){
if (arrOfNames || arrOfRanges == null){
initializeGame();
Logger.log('Game Initialized')
}
else {
Logger.log('Data Available')
}
};
I'm aware this is likely sloppy, but stay with me
This function works as intended, as does the following:
function reqVal(valname,x){
if (x == 0){
var nameArr = convToString(arrOfNames);
var valIndex = nameArr.indexOf("" + valname)
return arrOfRanges[valIndex];
}
else {
var nameArr = convToString(arrOfNames);
var valIndex = nameArr.indexOf("" + valname)
return valIndex;
}
};
Again, very very sloppy but Ill clean things up once I can make them function
Both of these scripts work fine on their own and return what I need. But if I have a third script:
function test(){
valData();
var valNum = reqVal('curHP', 0);
var valIndex = reqVal('curHP',1)
var newNum = valNum - 5;
Logger.log(valNum)
Logger.log(newNum)
Logger.log(valIndex)
};
The reqVal() function fails due to the asynchronous nature of GAS and the Cache having expired, but the valData() function succeeds and produces the needed array. So, I know I need to add a promise in valData() that the reqVal() function can read from but have no idea how to format that as examples I've seen have been very unclear.

Chrome extension: Get the text of a web page from given url

First, I'm completly newbie making chrome extension, then in a part of the chrome extension I will receive differents urls and I want to store the text of the web page to process it later, resulting in an array of boolean variables, each associated with the given url. Schematically it would be something like this:
var result;
function process(text){
if something -> result.push(true);
if not -> result.push(false);
}
function main(){
for (i...){
url = given[i];
text = getHTMLText(url);
process(text);
}
final();//when the loop finish activate another function that use the global variable: result
}
I have problems with main function, first I have tried with synchronous XMLHttpRequest, although it works it's very slow and chrome always give the warning that synchronous XMLHttpRequest is deprecated.
for (var i = 0; i < urls.length; i++){
url = urls[i];
var req = new XMLHttpRequest();
req.open('GET', url, false);
req.send(null);
if (req.status == 200) detecting(req.responseText);
};
Other solution that I find was use fetch(url), but the code that I find I don't fully understand. Although the returned text works correctly but then the proccess function give different results on each page update.
for (var i = 0; i < urls.length; i++){
url = urls[i];
fetch(url).then(function(response) {
response.text().then(function(text) {
detecting(text);
});
});
};
Other problem, but this is because of the little knowledge I have of fetch(), was that I can't store the text out of the fetch(), every time I do console.log give undefined, this greatly complicates the processing of the text for me.
I have seen that maybe it can be done through extension APIs of chrome but I can't see how to do it.

The algorithm shown in your main pseudocode can be implemented easily by using async/await and Promise.all, without a for loop:
(async () => {
const results = await Promise.all(urls.map(processUrl));
console.log(results);
// further processing must be also inside this IIFE
})();
async function processUrl(url) {
try {
const text = await (await fetch(url)).text();
return {url, text, status: detecting(text)};
} catch (error) {
return {url, error};
}
}

Race conditions using Office.js in Excel

I'm encountering some sort of race condition in the following code where I'm trying to write the response of an HTTP request to the active cell. I've read some possible solutions to the "InvalidObjectPath" errors from Office.js (I'm using ScriptLab specifically), but I don't think I'm trying to use anything across multiple contexts.
The current behavior works sometimes, but other times nothing will get written to the cell.
var counter = 0;
$("#run").click(run);
async function run() {
try {
await Excel.run(async (ctx) => {
var user;
const sUrl = "https://jsonplaceholder.typicode.com/users/1";
var client = new HttpClient();
var range = ctx.workbook.getSelectedRange();
counter++;
client.get(sUrl, function (response) {
var obj = JSON.parse(response);
user = obj.username;
range.values = [[user + counter]];
ctx.sync();
});
await ctx.sync();
});
}
catch (error) {
OfficeHelpers.UI.notify(error);
OfficeHelpers.Utilities.log(error);
}
}
var HttpClient = function() {
this.get = function(aUrl, aCallback) {
var anHttpRequest = new XMLHttpRequest();
anHttpRequest.onreadystatechange = function() {
if (anHttpRequest.readyState == 4 && anHttpRequest.status == 200)
aCallback(anHttpRequest.responseText);
}
anHttpRequest.open( "GET", aUrl, true );
anHttpRequest.send(null);
}
}

The issue is that you're not awaiting the completion of client.get. This means that [some of the time], the Excel.run will complete and "garbage-collect"(ish) some of the objects (range) before the callback inside of client.get is executed.
You can solve the issue in a number of ways:
Do the call to the web service before you execute the Excel.run. In your example here (which may not be realistic for many other scenarios, but it is here), you're not actually relying on anything from the document at all before you do your web call. In that case, no need to be inside the Excel.run at all, you can have Excel.run be part of the callback on the web service call.
Wrap your web-service call in a Promise, so that it can be awaited. Something like this:
var HttpClient = function() {
this.get = function(aUrl) {
return new Promise(function (resolve, reject) {
var anHttpRequest = new XMLHttpRequest();
anHttpRequest.onreadystatechange = function () {
if (anHttpRequest.readyState == 4 && anHttpRequest.status == 200) {
resolve(anHttpRequest.responseText);
} else {
reject(anHttpRequest.statusText);
}
}
anHttpRequest.open("GET", aUrl, true);
anHttpRequest.send(null);
});
}
}
I describe both approaches (and much more...) in a book that I've been writing about Building Office Add-ins using Office.js: https://leanpub.com/buildingofficeaddins/. I'm pasting in a few screenshots below from some of the relevant book content.
BTW, I should say that getting the selection is one of the few times when you don't want to delay a sync, as you want to capture the fleeting point-in-time selection rather than what will become the selection X seconds from now, once the web call succeeds. So this is one of the few cases where you may want to insert an extra await context.sync() even if you don't technically need it. See section "5.8.2: When to sync" in the book for more info.
=====
Promisifying an API:
=====
From about Promises:
=====
From the implementation details section:

Concept - Designing a collapsible queue for asynchronous resources

I've noticed that the size of a file requested will effect how long the response takes for ajax calls. So if I fire 3 ajax GET requests for files of varying size, they may arrive in any order. What I want to do is guarantee the ordering when I append the files to the DOM.
How can I set up a queue system so that when I fire A1->A2->A3. I can guarantee that they are appeneded as A1->A2->A3 in that order.
For example, suppose A2 arrives before A1. I would want the action to wait upon the arrival and loading of A1.
One idea is to create a status checker using a timed callback as such
// pseudo-code
function check(ready, fund) {
// check ready some how
if (ready) {
func();
} else {
setTimeout(function () {
check(ready, fund);
}, 1); // check every msec
}
}
but this seems like a resource heavy way, as I fire the same function every 1msec, until the resources is loaded.
Is this the right path to complete this problem?

status checker using a 1msec-timed callback - but this seems like a resource heavy way; Is this the right path to complete this problem?
No. You should have a look at Promises. That way, you can easily formulate it like this:
var a1 = getPromiseForAjaxResult(ressource1url);
var a2 = getPromiseForAjaxResult(ressource2url);
var a3 = getPromiseForAjaxResult(ressource3url);
a1.then(function(res) {
append(res);
return a2;
}).then(function(res) {
append(res);
return a3;
}).then(append);
For example, jQuery's .ajax function implements this.

You can try something like this:
var resourceData = {};
var resourcesLoaded = 0;
function loadResource(resource, callback) {
var xhr = new XMLHttpRequest();
xhr.onload = function() {
var state = this.readyState;
var responseCode = request.status;
if(state == this.DONE && responseCode == 200) {
callback(resource, this.responseText);
}
};
xhr.open("get", resource, true);
xhr.send();
}
//Assuming that resources is an array of path names
function loadResources(resources) {
for(var i = 0; i < resources.length; i++) {
loadResource(resources[i], function(resource, responseText) {
//Store the data of the resource in to the resourceData map,
//using the resource name as the key. Then increment the
//resource counter.
resourceData[resource] = responseText;
resourcesLoaded++;
//If the number of resources that we have loaded is equal
//to the total number of resources, it means that we have
//all our resources.
if(resourcesLoaded === resources.length) {
//Manipulate the data in the order that you desire.
//Everything you need is inside resourceData, keyed
//by the resource url.
...
...
}
});
}
}
If certain components must be loaded and executed before (like certain JS files) others, you can queue up your AJAX requests like so:
function loadResource(resource, callback) {
var xhr = new XMLHttpRequest();
xhr.onload = function() {
var state = this.readyState;
var responseCode = request.status;
if(state == this.DONE && responseCode == 200) {
//Do whatever you need to do with this.responseText
...
...
callback();
}
};
xhr.open("get", resource, true);
xhr.send();
}
function run() {
var resources = [
"path/to/some/resource.html",
"path/to/some/other/resource.html",
...
"http://example.org/path/to/remote/resource.html"
];
//Function that sequentially loads the resources, so that the next resource
//will not be loaded until first one has finished loading. I accomplish
//this by calling the function itself in the callback to the loadResource
//function. This function is not truly recursive since the callback
//invocation (even though it is the function itself) is an independent call
//and therefore will not be part of the original callstack.
function load(i) {
if (i < resources.length) {
loadResource(resources[i], function () {
load(++i);
});
}
}
load(0);
}
This way, the next file will not be loaded until the previous one has finished loading.
If you cannot use any third-party libraries, you can use my solution. However, your life will probably be much easier if you do what Bergi suggested and use Promises.

There's no need to call check() every millisecond, just run it in the xhr's onreadystatechange. If you provide a bit more of your code, I can explain further.

I would have a queue of functions to execute and each of them checks the previous result has completed before executing.
var remoteResults[]
function requestRemoteResouse(index, fetchFunction) {
// the argument fetchFunction is a function that fetches the remote content
// once the content is ready it call the passed in function with the result.
fetchFunction(
function(result) {
// add the remote result to the list of results
remoteResults[index] = result
// write as many results as ready.
writeResultsWhenReady(index);
});
}
function writeResults(index) {
var i;
// Execute all functions at least once
for(i = 0; i < remoteResults.length; i++) {
if(!remoteResults[i]) {
return;
}
// Call the function that is the ith result
// This will modify the dom.
remoteResults[i]();
// Blank the result to ensure we don't double execute
// Store a function so we can do a simple boolean check.
remoteResults[i] = function(){};
}
}
requestRemoteResouse(0, [Function to fetch the first resouse]);
requestRemoteResouse(1, [Function to fetch the second resouse]);
requestRemoteResouse(2, [Function to fetch the thrid resouse]);
Please note that this is currently O(n^2) for simplicity, it would get faster but more complex if you stored an object at every index of remoteResults, which had a hasRendered property. Then you would only scan back until you found a result that had not yet occurred or one that has been rendered.