We have a Progressive Web App that prompts the user with the "Add to home screen" banner.
Adding to the homescreen works great, but after the user launches the page from the Home Screen it will sometimes still prompt them to install the app again. I'm posting here because all the resources I have found don't talk about this issue or how to solve it.
TL;DR Launching the app from the home screen still asks them to install the app with the "Add to home screen" prompt.
As suggested by #Mr.Rebot, I developed a little piece of code to solve the problem.
This is the result code:
window.addEventListener("beforeinstallprompt", (ev) => {
if (isStandalone()) {
// PWA already installed.
event.preventDefault();
return false;
} else {
// PWA not installed.
}
});
function isStandalone() {
// Check if device supports service workers
if (!('serviceWorker' in window.navigator)) return false;
// Check for Android
if (window.matchMedia('(display-mode: standalone)').matches) return true;
// Check for iOS
if (window.navigator["standalone"] == true) return true;
return false;
}
Can a "pure" HTML5/Javascript (progressive) web application intercept the mobile device back button in order to avoid the App to exit?
This question is similar to this one but I want to know if it is possible to achieve such behavior without depending on PhoneGap/Ionic or Cordova.
While the android back button cannot be directly hooked into from within a progressive web app context, there exists a history api which we can use to achieve your desired result.
First up, when there's no browser history for the page that the user is on, pressing the back button immediately closes the app.
We can prevent this by adding a previous history state when the app is first opens:
window.addEventListener('load', function() {
window.history.pushState({}, '')
})
The documentation for this function can be found on mdn:
pushState() takes three parameters: a state object, a title (which is currently ignored), and (optionally) a URL[...] if it isn't specified, it's set to the document's current URL.
So now the user has to press the back button twice. One press brings us back to the original history state, the next press closes the app.
Part two is we hook into the window's popstate event which is fired whenever the browser navigates backwards or forwards in history via a user action (so not when we call history.pushState).
A popstate event is dispatched to the window each time the active history entry changes between two history entries for the same document.
So now we have:
window.addEventListener('load', function() {
window.history.pushState({}, '')
})
window.addEventListener('popstate', function() {
window.history.pushState({}, '')
})
When the page is loaded, we immediately create a new history entry, and each time the user pressed 'back' to go to the first entry, we add the new entry back again!
Of course this solution is only so simple for single-page apps with no routing. It will have to be adapted for applications that already use the history api to keep the current url in sync with where the user navigates.
To do this, we will add an identifier to the history's state object. This will allow us to take advantage of the following aspect of the popstate event:
If the activated history entry was created by a call to history.pushState(), [...] the popstate event's state property contains a copy of the history entry's state object.
So now during our popstate handler we can distinguish between the history entry we are using to prevent the back-button-closes-app behaviour versus history entries used for routing within the app, and only re-push our preventative history entry when it specifically has been popped:
window.addEventListener('load', function() {
window.history.pushState({ noBackExitsApp: true }, '')
})
window.addEventListener('popstate', function(event) {
if (event.state && event.state.noBackExitsApp) {
window.history.pushState({ noBackExitsApp: true }, '')
}
})
The final observed behaviour is that when the back button is pressed, we either go back in the history of our progressive web app's router, or we remain on the first page seen when the app was opened.
#alecdwm, that is pure genius!
Not only does it work on Android (in Chrome and the Samsung browser), it also works in desktop web browsers. I tested it on Chrome, Firefox and Edge on Windows, and it's likely the results would be the same on Mac. I didn't test IE because eew. Even if you're mostly designing for iOS devices that have no back button, it's still a good idea to ensure that Android (and Windows Mobile... awww... poor Windows Mobile) back buttons are handled so that the PWA feels much more like a native app.
Attaching an event listener to the load event didn't work for me, so I just cheated and added it to an existing window.onload init function I already had anyhow.
Keep in mind that it might frustrate users who would actually want to really Go Back to whatever web page they were looking at before navigating to your PWA while browsing it as a standard web page. In that case, you can add a counter and if the user hits back twice, you can actually allow the "normal" back event to happen (or allow the app to close).
Chrome on Android also (for some reason) added an extra empty history state, so it took one additional Back to actually go back. If anyone has any insight on that, I'd be curious to know the reason.
Here's my anti-frustration code:
var backPresses = 0;
var isAndroid = navigator.userAgent.toLowerCase().indexOf("android") > -1;
var maxBackPresses = 2;
function handleBackButton(init) {
if (init !== true)
backPresses++;
if ((!isAndroid && backPresses >= maxBackPresses) ||
(isAndroid && backPresses >= maxBackPresses - 1)) {
window.history.back();
else
window.history.pushState({}, '');
}
function setupWindowHistoryTricks() {
handleBackButton(true);
window.addEventListener('popstate', handleBackButton);
}
This approach has a couple of improvements over existing answers:
Allows the user to exit if they press back twice within 2 seconds: The best duration is debatable but the idea of allowing an override option is common in Android apps so it's often the correct approach.
Only enables this behaviour when in standalone (PWA) mode: This ensures the website keeps behaving as the user would expect when within an Android web browser and only applies this workaround when the user sees the website presented as a "real app".
function isStandalone () {
return !!navigator.standalone || window.matchMedia('(display-mode: standalone)').matches;
}
// Depends on bowser but wouldn't be hard to use a
// different approach to identifying that we're running on Android
function exitsOnBack () {
return isStandalone() && browserInfo.os.name === 'Android';
}
// Everything below has to run at page start, probably onLoad
if (exitsOnBack()) handleBackEvents();
function handleBackEvents() {
window.history.pushState({}, '');
window.addEventListener('popstate', () => {
//TODO: Optionally show a "Press back again to exit" tooltip
setTimeout(() => {
window.history.pushState({}, '');
//TODO: Optionally hide tooltip
}, 2000);
});
}
i did not want to use native javascript functions to handle this inside of a react app, so i scoured solutions
that used react-router or react-dom-router, but in the end, up against a deadline, native js is
what got it working. Added the following listeners inside inside componentDidMount() and setting the history
to an empty state
window.addEventListener('load', function() {
window.history.pushState({}, '')
})
window.addEventListener('popstate', function() {
window.history.pushState({}, '')
})
this worked fine on the browser, but was still not working in the PWA on mobile
finally a colleague found out that triggering the history actions via code is what somehow initiated the listeners
and voila! everything fell in place
window.history.pushState(null, null, window.location.href);
window.history.back();
window.history.forward();
In my case, I had a SPA with different drawers on that page and I want them to close when User hits back button..
you can see different drawers in the image below:
I was managing states(eg open or close) of all drawers at a central location (Global state),
I added the followin code to a useEffect hook that runs only once on loading of web app
// pusing initial state on loading
window.history.pushState(
{ // Initial states of drawers
bottomDrawer,
todoDetailDrawer,
rightDrawer,
},
""
);
window.addEventListener("popstate", function () {
//dispatch to previous drawer states
// dispatch will run when window.history.back() is executed
dispatch({
type: "POP_STATE",
});
});
and here is what my dispatch "POP_STATE" was doing,
if (window.history.state !== null) {
const {
bottomDrawer,
rightDrawer,
todoDetailDrawer,
} = window.history.state; // <- retriving state from window.history
return { // <- setting the states
...state,
bottomDrawer,
rightDrawer,
todoDetailDrawer,
};
It was retriving the last state of drawers from window.history and setting it to current state,
Now the last part, when I was calling window.history.pushState({//object with current state}, "title", "url eg /RightDrawer") and window.history.back()
very simple,
window.history.pushState({//object with current state}, "title", "url eg /RightDrawer") on every onClick that opens the drawer
&
window.history.back() on every action that closes the drawer.
I want to close my app when user force close.
Any event arise for force close in ionic application ?
Any plugin for force close event handling in ionic app ?
example:
A common piece of functionality for native mobile applications is the ability to logged out if the user closes the application(force stop/force close).
How can this be achieved for a Cordova / Ionic / PhoneGap ?
Put the following code accordingly to your angular.run configuration, and that's it. You can even add some checks, for example using a boolean value in a Service or a check to the current state to decide if prompt to the user the closing app notice or not.
.run(function($ionicPlatform, $ionicPopup) {
$ionicPlatform.onHardwareBackButton(function () {
if(true) { // your check here
$ionicPopup.confirm({
title: 'System warning',
template: 'are you sure you want to exit?'
}).then(function(res){
if( res ){
navigator.app.exitApp();
}
})
}
})
});
More...
I have searched all over the web and found different ways of closing a PhoneGap App. I tested all of them and none work. At least on Android.
Question:
Is it possible (By Feb 2014) to have a close button in a PhoneGap App on Android?
Thanks
This doesn't work:
function CloseApp() {
if (confirm('Close this App?')){
if (navigator.app) {
navigator.app.exitApp();
}else if (navigator.device) {
navigator.device.exitApp();
}
}
}
Is
navigator.app.exitApp()
really killing/closing the android app with phonegap?
I use cordova and have the same issue. Above mentioned code is just putting the app into background - I checked the running tasks (android task manager) after above code got executed by the app.
I am confused on why you want a button to close the app. Android already has a back button when clicked enough times will take the user back to the phone's main screen. There is also a home button that takes the user out of an app. Once, out of the app the user can "kill" the app through a task manager.
navigator.app.exitApp()
works and I use it in all my cordova apps. Check the rest of your code.
As ejwill said, having a "close" button is a bad idea. On Android I call exitApp when the user is the home page of my app and he presses the backbutton:
function onDeviceReady() {
document.addEventListener("backbutton", onBackKey, false);
}
function onBackKey( event ) {
var l = window.location.toString();
var parts = l.split('#/'); // this works only if you are using angularjs
var page = parts[1];
if (page == 'home') {
navigator.app.exitApp();
} else {
// do something else... one option is:
navigator.app.backHistory();
}
}
My 2c.
Problem:
I'm trying to avoid the "web page not found", or at least to display a customized error page.
Context:
I use the cordova trick:
if (navigator.network.connection.type == Connection.NONE)
{
window.location="offline/index.html";
}
else
{
window.location="http://myurl.com";
}
But in my tablet, if there's no connection, I have the ugly "WebPage not found".
There's maybe something wrong in my code, but in all case I would like to find a way to avoid this page and to show my own.
I will be very happy if somebody here can tell me where to give a look.
Stef
PS : the "Page Not found" appears when the website is down. It's not related to the event offline. You can have internet, and the server can be down. In that case, I want to display my own error page. Thanks!
There is an event offline available in Cordova. You could add event listeners to this and do required changes in its callback. If you are using deviceready event it will be called only once when your app is done loading. But if you add offline & online listeners you can alert user each time network goes down/up.
document.addEventListener("offline", onOffline, false);
function onOffline() {
// Handle the offline event
}
http://docs.phonegap.com/en/2.9.0/cordova_events_events.md.html#offline