I show a 'sticky' notification like this:
function show(text) {
let alreadyOn = false; // ??? how to get this ???
if (!alreadyOn) {
new Notification(text, {
requireInteraction : true
});
}
}
Notification.requestPermission();
show("first");
setTimeout(() => show("second"), 1000);
(note this just a sample and you need to permit notification the first time it runs and try again)
Is there a way for my code to later determine if this notification is still on or the user already dismissed it ? That is how to determine alreadyOn above ?
You can add an event handler with Notification.onclose method to do something when the Notification is closed by the user.
Notification.onclose = function () {
// do something...
}
I am new to react.js.
I have a simple page with table. When I reload the page, state is getting lost.
Is there a way to detect the browser refresh ?
The event beforeunload is executed just before window browser is being refreshed. Event is cancellable.
window.beforeunload = (e) => {
console.log('Stop this');
e.preventDefault()
e.returnValue = '';
};
When using React an option is to take control in your Application component, or your most higher order component, in the componentDidMount lifecycle method as #georgim suggested instead componentWillUnmount as I first suggested, and manage there what you want to achieve.
With [react-beforeunload][1] you can track the page changes easily
import { useBeforeunload } from 'react-beforeunload'
const App = () => {
const [preventMultiSubmit, setPreventMultiSubmit] = useState(false)
}
const pageRefConf = useBeforeunload((event) => {
if (preventMultiSubmit) {
event.preventDefault()
}
})
useEffect(() => {
window.addEventListener('beforeunload', pageRefConf)
return () => {
window.removeEventListener('beforeunload', pageRefConf)
}
}, [])
This worked for me. I hope this one will work for you too.
[1]: https://www.npmjs.com/package/react-beforeunload
Try this one. This worked for me.
if (window.performance) {
if (performance.navigation.type == 1) {
alert( "This page is reloaded" );
} else {
alert( "This page is not reloaded");
}
}
I have developed a windows 10 universal app using Html,css and JS. For allowing inline scripts i am using ms-appx-web context and has set ms-appx-web:///login.html as start page in manifest.
Whenever I open my app in windows 10 mobile it works fine but if I switch to another app and then go to app again by selecting it from windows app list. Then it instead of resuming app from saved state it restarts it.
(function () {
"use strict";
var app = WinJS.Application;
var activation = Windows.ApplicationModel.Activation;
app.onactivated = function (args) {
if (args.detail.kind === activation.ActivationKind.launch) {
if (args.detail.previousExecutionState === activation.ApplicationExecutionState.terminated) {
}
if (WinJS.Application.sessionState.url) {
localStorage.setItem("UserName", WinJS.Application.sessionState.name);
window.location = WinJS.Application.sessionState.url;
}
args.setPromise(WinJS.UI.processAll().then(function () {
}));
}
};
app.oncheckpoint = function (args) {
var location = window.location.href;
var name = localStorage.getItem("UserName");
WinJS.Application.sessionState.name = name;
WinJS.Application.sessionState.url = location;
};
Windows.UI.WebUI.WebUIApplication.addEventListener("resuming", function (args) {
if (WinJS.Application.sessionState) {
window.location = WinJS.Application.sessionState.url;
localStorage.setItem("UserName", WinJS.Application.sessionState.name);
}
}, false);
Windows.UI.WebUI.WebUIApplication.addEventListener("suspending", function (args) {
var location = window.location.href;
var name = localStorage.getItem("UserName");
WinJS.Application.sessionState.name = name;
WinJS.Application.sessionState.url = location;
}, false);
app.start();
})();
Can anyone suggest me what am I doing wrong?
I changed my app.onactivated event in main.js
app.onactivated = function (args) {
if (args.detail.kind === activation.ActivationKind.launch) {
if (args.detail.previousExecutionState !== activation.ApplicationExecutionState.terminated) {
} else {
}
args.setPromise(WinJS.UI.processAll());
var name = Windows.Storage.ApplicationData.current.roamingSettings.values["name"];
var url = Windows.Storage.ApplicationData.current.roamingSettings.values["url"];
if (name) {
localStorage.setItem("UserName", name);
}
if (url) {
window.location.href = url;
}
}
};
But it stops running on window.location.href = url; line.
What i am trying to do is store username and current url on suspending event and want to restore it on resume event (when user opens app from app list which is already running.)
but if I switch to another app and then go to app again by selecting it from windows app list. Then it instead of resuming app from saved state it restarts it.
I think you are not using Single-Page Navigation for your app.
Please refer to Single-page navigation: the recommended model:
The script context is destroyed and must be initialized again. The app might receive system events but not handle them because the script context is being destroyed and reinitialized.
So the script context is already destroyed after you navigated to other page.
To fix the problem, the best solution is to make your app a single paged application. And navigate pages using PageControl. You can refer to Quickstart: Using single-page navigation to get started.
Update:
but when I use window.location.href for redirecting in main.js it closes app.
It's because you are using it in WinJS script. When you are leaving the page WinJS script context will be destroyed and thus executing the codes inside crash the app. To fix this you can use windows lifecycle API instead:
var roaming=Windows.Storage.ApplicationData.current.roamingSettings;
Windows.UI.WebUI.WebUIApplication.addEventListener("activated", function (args) {
if (args.detail[0].kind === activation.ActivationKind.launch) {
if (roaming.values["currentUri"]) {
window.location.href = roaming.values["currentUri"];
}
}
});
Windows.UI.WebUI.WebUIApplication.addEventListener("suspending", function (args) {
roaming.values["currentUri"] = window.location.href;
roaming.values["UserName"] = evt.srcElement.value;
//save the other information of the page here
});
Windows.UI.WebUI.WebUIApplication.addEventListener("resuming", function (args) {
var roam = Windows.Storage.ApplicationData.current.roamingSettings;
if (roam) {
if (roam["currentUri"])
{
window.location.href = roam["currentUri"];
}
}
}, false);
You can also refer to my demo.
Notes: If you don't use WinJS at all, just remove the reference. Loading WinJS library on every page is not efficient.
I have changed my main.js as :
(function () {
"use strict";
//No need of WinJS
var activation = Windows.ApplicationModel.Activation;
var roaming = Windows.Storage.ApplicationData.current.roamingSettings;
// For App Start Up
Windows.UI.WebUI.WebUIApplication.addEventListener("activated", function (args) {
if (args.detail[0].kind === activation.ActivationKind.launch) {
if (roaming.values["currentUri"]) {
if (roaming.values["UserName"])
{
localStorage.setItem("UserName", roaming.values["UserName"]);
window.location.href = roaming.values["currentUri"];
}
}
}
});
// For App Suspension
Windows.UI.WebUI.WebUIApplication.addEventListener("suspending", function (args) {
roaming.values["currentUri"] = window.location.href;
roaming.values["UserName"] = localStorage.getItem("UserName");
});
// For Resuming App
Windows.UI.WebUI.WebUIApplication.addEventListener("resuming", function (args) {
var roam = Windows.Storage.ApplicationData.current.roamingSettings;
if (roam) {
if (roam.values["currentUri"]) {
localStorage.setItem("UserName", roam.values["UserName"]);
window.location.href = roam.values["currentUri"];
}
}
}, false);
// not working backpressed event
Windows.UI.WebUI.WebUIApplication.addEventListener("backpressed", function (args) {
// to do
}, false);})();
Everything is working fine. But I dont know how to add back key press event without using winjs.
Can anyone suggest me?
How to add back key press event without winjs?
This is undoubtedly a stupid problem where I'm just doing something simple wrong.
I have a page with several directives, loading their templates and controllers. All of which is working fine except for this one.
Using the controller as model, this. is the same as $scope.. So in my controller I have:
var self = this;
this.states = { showControls: false, showVideo: false }
this.showVideo = function() { self.states.showVideo = true; }
this.showControls = function() { self.states.showControls = true; }
$scope.$on(Constants.EVENT.START_WEBCAM, self.showVideo)
$scope.$on(Constants.EVENT.VIDEO_SUCCESS, self.showControls)
In the view I have a button to reveal this part of the view and subsequently request access to your webcam. Clicking the button broadcasts an event with $rootScope.$broadcast from the parent controller.
When the user grants access to the webcam (handled in the directive's link function) it broadcasts another event the same way.
Both methods are triggered by listening with $scope.$on, and both methods fire as they should. However, the showVideo method successfully updates its associated state property, and the showControls method does not. What am I doing wrong?
Using the debug tool it looks like states.showControls is being set to true, but this change isn't reflected in the view, and adding a watcher to the states object doesn't detect any change at this point either. It does when I set showVideo.
EDIT
This part is in the directive:
if (Modernizr && Modernizr.prefixed('getUserMedia', navigator)) {
userMedia = Modernizr.prefixed('getUserMedia', navigator);
}
var videoSuccess = function(stream) {
// Do some stuff
$rootScope.$broadcast(Constants.EVENT.VIDEO_SUCCESS);
}
scope.$on(Constants.EVENT.START_WEBCAM, function() {
if (MediaStreamTrack && MediaStreamTrack.getSources) {
MediaStreamTrack.getSources(function(sourceInfo) {
var audio = null;
var video = null;
_.each(sourceInfo, function(info, i) {
if (info.kind === "audio") {
audio = info.id;
} else if (info.kind === "video") {
video = info.id;
} else {
console.log("random unknown source: ", info);
}
});
if (userMedia) { userMedia(getReqs(), videoSuccess, error); }
});
}
});
I'm just thinking about the whole site registration process.
A user goes to your site, signs up, and then you tell him you've sent him an email and he needs to verify his email address. So he hits Ctrl+T, pops open a new tab, hits his Gmail fav button, doesn't read a word of your lengthy welcome email, but clicks the first link he sees. Gmail opens your site in yet another tab...
He doesn't need nor want two tabs for your site open, he just wants to view that darn page you've disallowed him access to until he registers.
So what do we do? I saw one site (but I forget what it was) that did a really good job, and it actually refreshed the first tab I had open without me having to press anything.
I'm thinking, it might be nice if we can detect if the user already has a tab to your site open, we could either close the new verification-tab automatically, or tell him he can close it can go back to his other tab (which we've now refreshed and logged him in).
Or, maybe when he got your annoying "please check your email" message, he went directly to his email, replacing your site with his email knowing full well that the email will link him back to the site again. In that case, we don't want to close the tab, but maybe could have saved his location from before, and redirect him there again?
Anyway, that's just the use case... the question still stands. Can we detect if a user already has a tab to your site open?
This question is not about how to detect when a user has completed the sign-up process. Ajax polling or comet can solve that issue. I specifically want to know if the user already has a tab open to your site or not.
I'm fairly late to the party here (over a year), but I couldn't help but notice that you'd missed an incredibly easy and elegant solution (and probably what that website you saw used).
Using JavaScript you can change the name of the window you currently have open through:
window.name = "myWindow";
Then when you send out your confirmation email simply do (assuming you're sending a HTML email):
Verify
Which should result in the verificationLink opening up inside the window your website was already loaded into, if it's already been closed it'll open up a new tab with the window name specified.
You can stop the page functionality when user opened another tab or another window or even another browser
$(window).blur(function(){
// code to stop functioning or close the page
});
You can send an AJAX request every X seconds from the original tab that asks the server if it received a request from the email.
You cannot close the second tab automatically, but you could have it ask the server after 3X seconds whether it heard from the first tab.
What I have here is a little bit different use case to you but it detects if the site is being accessed in another tab. In this case I wanted to limit people using some call center pages to only one tab. It works well and is purely client-side.
// helper function to set cookies
function setCookie(cname, cvalue, seconds) {
var d = new Date();
d.setTime(d.getTime() + (seconds * 1000));
var expires = "expires="+ d.toUTCString();
document.cookie = cname + "=" + cvalue + ";" + expires + ";path=/";
}
// helper function to get a cookie
function getCookie(cname) {
var name = cname + "=";
var decodedCookie = decodeURIComponent(document.cookie);
var ca = decodedCookie.split(';');
for(var i = 0; i < ca.length; i++) {
var c = ca[i];
while (c.charAt(0) == ' ') {
c = c.substring(1);
}
if (c.indexOf(name) == 0) {
return c.substring(name.length, c.length);
}
}
return "";
}
// Do not allow multiple call center tabs
if (~window.location.hash.indexOf('#admin/callcenter')) {
$(window).on('beforeunload onbeforeunload', function(){
document.cookie = 'ic_window_id=; expires=Thu, 01 Jan 1970 00:00:00 UTC; path=/;';
});
function validateCallCenterTab() {
var win_id_cookie_duration = 10; // in seconds
if (!window.name) {
window.name = Math.random().toString();
}
if (!getCookie('ic_window_id') || window.name === getCookie('ic_window_id')) {
// This means they are using just one tab. Set/clobber the cookie to prolong the tab's validity.
setCookie('ic_window_id', window.name, win_id_cookie_duration);
} else if (getCookie('ic_window_id') !== window.name) {
// this means another browser tab is open, alert them to close the tabs until there is only one remaining
var message = 'You cannot have this website open in multiple tabs. ' +
'Please close them until there is only one remaining. Thanks!';
$('html').html(message);
clearInterval(callCenterInterval);
throw 'Multiple call center tabs error. Program terminating.';
}
}
callCenterInterval = setInterval(validateCallCenterTab, 3000);
}
To flesh out John's answer, here is a working solution that uses plain JS and localStorage and updates the DOM with the count of the currently open tabs. Note that this solution detects the number of open tabs/windows for a given domain within one browser, but does not maintain the count across different browsers.
It uses the storage event to keep the count synchronized across all open tabs/windows without any need for refreshing the page.
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<title></title>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<meta name="robots" content="noindex, nofollow">
<meta name="googlebot" content="noindex, nofollow">
<meta name="viewport" content="width=device-width, initial-scale=1">
<script>
(function() {
var stor = window.localStorage;
window.addEventListener("load", function(e) {
var openTabs = stor.getItem("openTabs");
if (openTabs) {
openTabs++;
stor.setItem("openTabs", openTabs)
} else {
stor.setItem("openTabs", 1)
}
render();
})
window.addEventListener("unload", function(e) {
e.preventDefault();
var openTabs = stor.getItem("openTabs");
if (openTabs) {
openTabs--;
stor.setItem("openTabs", openTabs)
}
e.returnValue = '';
});
window.addEventListener('storage', function(e) {
render();
})
function render() {
var openTabs = stor.getItem("openTabs");
var tabnum = document.getElementById("tabnum");
var dname = document.getElementById("dname");
tabnum.textContent = openTabs;
dname.textContent = window.location.host
}
}());
</script>
</head>
<body>
<div style="width:100%;height:100%;text-align:center;">
<h1 >You Have<h1>
<h1 id="tabnum">0</h1>
<h1>Tab(s) of <span id="dname"></span> Open</h1>
</div>
</body>
</html>
To add to other answers:
You can also use localStorage. Have an entry like 'openedTabs'. When your page is opened, increase this number. When user leaves the page, decrease it.
The user will still have a session at the server. Why not store the user's location prior to registration, and when they confirm their registration, read the location back out of the session and redirect back to that page. No tab magic required. It's certainly not what I'd expect from a signup process.
It is possible to track number of tabs of your site opened by saving data in localstorage of each tab and counting the same, I created a github repository which can track number of tabs of your website a user has opened.
To use it Include tab-counter.js in your page and it will start tracking number of opened tabs.
console.log(tabCount.tabsCount());
Here's a system that uses broadcast channels for cross tab comms. It also assigns a unique ID per tab and manages the discovery of already opened tabs, for new tabs. Finally, using the ID as a stable index, it allows the user to rename their tabs. Tab closing events are handled via polling as well (unload events are unreliable).
This plugs into redux via the callbacks in the constructor. These are onNewTab, onDestroyTab, onRenameTab in this example.
import { setTabs } from './redux/commonSlice';
import { store } from './redux/store';
const promiseTimeout = (ms, promise) => {
let id;
let timeout = new Promise((resolve, reject) => {
id = setTimeout(() => {
reject('Timed out in ' + ms + 'ms.');
}, ms)
})
return Promise.race([
promise,
timeout
]).then((result) => {
clearTimeout(id);
return result;
})
};
// Promise that can be resolved/rejected outside of its constructor. Like a signal an async event has occured.
class DeferredPromise {
constructor() {
this._promise = new Promise((resolve, reject) => {
// assign the resolve and reject functions to `this`
// making them usable on the class instance
this.resolve = resolve;
this.reject = reject;
});
// bind `then` and `catch` to implement the same interface as Promise
this.then = this._promise.then.bind(this._promise);
this.catch = this._promise.catch.bind(this._promise);
this.finally = this._promise.finally.bind(this._promise);
this[Symbol.toStringTag] = 'Promise';
}
}
class TabManager {
tabCreateCallback = undefined;
tabDestroyCallback = undefined;
tabRenameCallback = undefined;
constructor(onNewTab, onDestroyTab, onRenameTab) {
this.tabCreateCallback = onNewTab.bind(this);
this.tabDestroyCallback = onDestroyTab.bind(this);
this.tabRenameCallback = onRenameTab.bind(this);
// creation time gives us a total ordering of open tabs, also acts as a tab ID
this.creationEpoch = Date.now();
this.channel = new BroadcastChannel("TabManager");
this.channel.onmessage = this.onMessage.bind(this);
// our current tab (self) counts too
this.tabs = [];
this.tabNames = {};
// start heartbeats. We check liveness like this as there is _no_ stable browser API for tab close.
// onbeforeunload is not reliable in all situations.
this.heartbeatPromises = {};
this.heartbeatIntervalMs = 1000;
setTimeout(this.doHeartbeat.bind(this), this.heartbeatIntervalMs);
}
doComputeNames() {
for (let i = 0; i < this.tabs.length; i++) {
const tab = this.tabs[i];
const name = this.tabNames[tab];
const defaultName = `Tab ${i + 1}`;
if (!name) {
this.tabNames[tab] = defaultName;
if (this.tabRenameCallback) {
this.tabRenameCallback(tab, name);
}
// if it's a default pattern but wrong inde value, rename it
} else if (name && this.isDefaultName(name) && name !== defaultName) {
this.tabNames[tab] = defaultName;
if (this.tabRenameCallback) {
this.tabRenameCallback(tab, name);
}
}
}
}
doHeartbeat() {
for (let tab of this.tabs) {
if (tab === this.creationEpoch) {
continue;
}
this.channel.postMessage({ type: "heartbeat_request", value: tab });
const heartbeatReply = new DeferredPromise();
heartbeatReply.catch(e => { });
// use only a fraction of poll interval to ensure timeouts occur before poll. Prevents spiral of death.
let heartbeatReplyWithTimeout = promiseTimeout(this.heartbeatIntervalMs / 3, heartbeatReply);
// destroy tab if heartbeat times out
heartbeatReplyWithTimeout.then(success => {
delete this.heartbeatPromises[tab];
}).catch(error => {
delete this.heartbeatPromises[tab];
this.tabs = this.tabs.filter(id => id !== tab);
this.tabs.sort();
this.doComputeNames();
if (this.tabDestroyCallback) {
this.tabDestroyCallback(tab);
}
});
this.heartbeatPromises[tab] = heartbeatReply;
}
// re-schedule to loop again
setTimeout(this.doHeartbeat.bind(this), this.heartbeatIntervalMs);
}
doInitialize() {
this.tabs = [this.creationEpoch];
this.doComputeNames();
if (this.tabCreateCallback) {
this.tabCreateCallback(this.creationEpoch);
}
this.channel.postMessage({ type: "creation", value: this.creationEpoch });
}
onMessage(event) {
if (event.data.type == "creation") {
const newTabId = event.data.value;
// add the new tab
if (!this.tabs.includes(newTabId)) {
this.tabs.push(newTabId);
this.tabs.sort();
this.doComputeNames();
if (this.tabCreateCallback) {
this.tabCreateCallback(newTabId);
}
}
// send all of the tabs we know about to it
this.channel.postMessage({ type: "syncnew", value: this.tabs });
// those tabs we just sent might already have custom names, lets send the older rename requests
// which would have had to have occured. I.E. lets replay forward time and sync the states of ours to theirs.
for (let tab of this.tabs) {
const name = this.tabNames[tab];
if (name && !this.isDefaultName(name)) {
this.notifyTabRename(tab, name);
}
}
} else if (event.data.type == "syncnew") {
let newTabs = [];
// just got a list of new tabs add them if we down't know about them
for (let id of event.data.value) {
if (!this.tabs.includes(id)) {
newTabs.push(id);
}
}
// merge the lists and notify of only newly discovered
if (newTabs.length) {
this.tabs = this.tabs.concat(newTabs);
this.tabs.sort();
this.doComputeNames();
for (let id of newTabs) {
if (this.tabCreateCallback) {
this.tabCreateCallback(id);
}
}
}
} else if (event.data.type == "heartbeat_request") {
// it's for us, say hi back
if (event.data.value === this.creationEpoch) {
this.channel.postMessage({ type: "heartbeat_reply", value: this.creationEpoch });
}
} else if (event.data.type == "heartbeat_reply") {
// got a reply, cool resolve the heartbeat
if (this.heartbeatPromises[event.data.value]) {
// try catch since this is racy, entry may have timed out after this check passed
try {
this.heartbeatPromises[event.data.value].resolve();
} catch {
}
}
} else if (event.data.type == "rename") {
// someone renamed themselves, lets update our record
const { id, name } = event.data.value;
if (this.tabs.includes(id)) {
this.tabNames[id] = name;
// first original (potentially illegal) rename callback first
if (this.tabRenameCallback) {
this.tabRenameCallback(id, name);
}
// force tab numbers back to consistent
this.doComputeNames();
}
}
}
setTabName(id, name) {
if (this.tabs.includes(id)) {
this.tabNames[id] = name;
this.notifyTabRename(id, name);
if (this.tabRenameCallback) {
this.tabRenameCallback(id, name);
}
// force tab numbers back to consistent
this.doComputeNames();
}
}
notifyTabRename(id, name) {
this.channel.postMessage({ type: "rename", value: { id, name } });
}
isDefaultName(name) {
return name.match(/Tab [0-9]+/)
}
getMyTabId() {
return this.creationEpoch;
}
getMyTabIndex() {
return this.tabs.findIndex(tab => tab === this.creationEpoch);
}
isMyTab(id) {
return id === this.creationEpoch;
}
getAllTabs() {
return this.tabs.map((tab, idx) => {
return { id: tab, index: idx, name: this.tabNames[tab] ?? "" };
}, this);
}
}
function onDestroyTab(id) {
store.dispatch(setTabs(this.getAllTabs()));
console.log(`Tab ${id} destroyed`);
}
function onNewTab(id) {
store.dispatch(setTabs(this.getAllTabs()));
console.log(`Tab ${id} created`);
}
function onRenameTab(id, name) {
store.dispatch(setTabs(this.getAllTabs()));
console.log(`Tab ${id} renamed to ${name}`);
}
const TabManager = new TabManager(onNewTab, onDestroyTab, onRenameTab);
export default TabManager;
Initialize it on page load
window.addEventListener("DOMContentLoaded", function (event) {
TabManager.doInitialize();
});
Access any of the methods on the static object at any time. Note that you can get rename events out of order from create / destroy. This could be resolved, but it wasn't important for me.