We Keep Coding

Detect Page Refresh or Navigation in Browser

I have a web app where a parent page displaying a list of records opens up a new tab ('child') to edit a clicked-on record. I want to track who has a page open, so I can display a message if more than one person is editing a unique record. This means reporting when a page is closed. I have assigned each page a GUID to facilitate recognition of the page instance.
So javascript in the browser needs to detect several scenarios:
browser tab closed
browser refresh
browser navigation to hyperlink
browser navigation forward/back
At the moment, all of these appear to trigger the window.onbeforeunload event. However I use this event to warn of changes in the underlying data, which means the event returns the confirmation text, and there is no way of knowing in this event if the user subsequently confirms or cancels the page unload. So I can't use this event to track page closure.
According to a number of sources the window.onunload event should be triggered in all of the above scenarios (and if it was, I could use it), but testing under Chrome on Windows is only triggering this event in scenario 1 (when the tab is closed). It works fine for that.
I'm pretty surprised by the lack of information around this - surely it's a bread and butter requirement in modern sites?
Has window.onunload been deprecated lately in some scenarios, or in some scenarios in some browsers? Without a reliable hook that takes place when the page is about to be replaced with some other information, it's impossible to monitor closing of a page. Any other workarounds?
I know that the two unload events suppress blocking functions (such as alerts) in the handler. However they appear to do hit breakpoints, do a console.log and allow Ajax calls just fine. I'm pretty sure they are not being fired in events 2,3 and 4 - it's not just that my debugging is being blocked.

While there appear to be answers on SO already (most of which don't work or are deprecated), I posted this because browser events are a shifting-sands scenario as security issues evolve, so I wanted to find out where we are in 2021.
Actually, it looks as if this might be the solution: https://developers.google.com/web/updates/2018/07/page-lifecycle-api#the-unload-event
Google discourages use of the unload event because it is (a) unreliable on mobiles and (b) blocks the caching of pages. It is also advised to only add the beforeunload event just before it is used, and to remove it afterwards, because it also blocks the caching of pages (I note that this is not really practical for me, however, as I use it to guard against unintentional closing of a page after a possibly significant amount of data has been entered, and this could happen at any moment).
So as of July 2018, and still best practice as of July 2021, this would be the recommended way to detect the unloading of a page:
const terminationEvent = 'onpagehide' in self ? 'pagehide' : 'unload';
addEventListener(terminationEvent, function(event) {
// handler code here ...
}, { capture: true });
This has been tested in a small ASP NET Core project using an AJAX callback to report the page termination, and appears to work reliably in Chrome and Edge. Also works in IE11 as long as
<meta http-equiv="x-ua-compatible" content="IE=edge">
is present.

Can't focus elements on load in Chrome - very weird bug (in Chrome?)

I have a very, very weird issue that only seems to be an issue in Chrome.
When a user comes on the website, the user cannot focus any element (via mouse click, if they focus it via tabbing, the elements don't get the 'focused' state either) and that's only an issue in Chrome. That is, until the user resizes the window, minimizes the window, opens a new tab, opens developer tools, etc. Reloading the page does nothing. However, as soon as focus is "enabled", the user can navigate/refresh with purging cache, etc., close the browser and open it again, and everything works normally - the elements get the 'focused' state normally.
This behaviour can only be reproduced in Chrome and not on localhost.
The difference between localhost and beta environment is:
beta env requires authentication (basic http auth)
files in development env are concated in a single JS and single CSS file and both are minimized
beta env includes hotjar, while there's no hotjar on localhost
There are no custom event listeners that would listen for the 'resize' event. There are no errors in console and all javascript that doesn't depend on focused element state gets executed correctly. Hover events and all CSS styling that depends on hovered state all work correctly.
The main issue is, that a form which has to be filled out and includes a datepicker, cannot be filled out and thus the users can't really interact with the page. Datepicker doesn't open and, as the input elements don't get the focused state, they don't visually change (CSS :focused selector isn't working either) and thus give the impression to the user that they cannot type in the normal text inputs (which works, after clicking on the input, it is possible to type in the input).
I have tried removing hotjar and the problem persisted. The only thing that made the problem go away was removing the basic auth, however, that is not an option in this stage (it's a closed beta test, so we need to limit the access only to the users with password).
I also find it extremely odd that basic auth would interfere with the focused state of elements, especially as the error persists after you refresh and only goes away as soon as you interact with browser itself (minimize, open new tab, do anything that resizes your browser window or document), after that it works correctly and there are no errors whatsoever.
The problem only started to appear recently, but I do not believe it's an issue with the app itself, as I tried rolling back to a couple months old build and the problem persists. All of that makes me believe it's a bug in Chrome, but what can be done to fix it?
EDIT: I also tried to add autofocus property to an input element and, in beta environment, it doesn't get focused.

So it seems it indeed is a Chrome bug that's present both on mobile (Android and iOS) Chrome browsers, as well as desktop Chrome browser (tested both on a Windows and a Mac). I submitted an official bug report. In the bug report, a fellow user made a website that's accessible only through basic auth and only has 2 basic inputs, the input should get a red border on focus. As expected, after opening the webpage in Chrome (for ease of use - incognito mode), the input doesn't get focus and the border doesn't change.
For those who are also affected by this bug in Chrome, you can track the bug progress here: https://bugs.chromium.org/p/chromium/issues/detail?id=740652
Meanwhile, here's a hacky solution for those interested:
$(document).on("ready", function() {
var $inputs = $("input");
$inputs.off("click.trick");
if (!sessionStorage.fixedChromeFocus) {
sessionStorage.fixedChromeFocus = "true";
$inputs.on("click.trick", function() {
var win = window.open("/", "_blank");
setTimeout(function() {win.close()}, 1);
$inputs.off("click.trick");
});
}
});
The goal is to, somehow, interact with the browser outside of the current page, to make it somehow lose focus. You cannot use JS to minimize browser, cannot resize it, cannot open dev tools. What you can do, though, is open a new window. Of course, if you open a new window immediately, a pop-up blocker (as most people have it) will block it and the window itself (or rather your current tab) won't lose focus. Opening a new window can only be done as a reaction to a user event (without triggering potential pop-up blocker).
I also use some browser detection so the code will only be executed for Chrome and, using server-side conditioning, only for builds that include basic auth.
What the code does, quite self evidently, is that as soon as a user clicks on an input, it opens a new tab and quickly closes it, 1ms later. To prevent this from happening all the time, on every page load, sessionStorage, which gets cleared automatically after tabs from that domain are closed, is used (and we've already established that once focus starts working correctly, it will work as long as you keep your browser open).
The effect of this code is that the user will see a quick white flash the first time he clicks on the input, but everything will work correctly

How would you stop a page from refreshing automatically?

I have a problem when I am trying to check the source of an interesting page which keeps refreshing automatically every 3-5 seconds (presumably due to some js script) which resets my Inspect Element Inspector window every time the page is refreshed.
Is there any other way other to stop that page from refreshing or perhaps the Inspector window from resetting itself other than turning on NoScript to stop the page from refreshing automatically?

Usually I just open DevTools, switch to the appropriate panel if necessary, and hit pause.
Opening DevTools: Via menus, or by press F12, Ctrl+Shift+I, or Cmd+Shift+I depending on browser and OS.
Switching panels: Pick the panel from the tabs at the top of DevTools. It'll be called "Debugger" (Firefox, IE) or "Sources" (Chrome) or similar.
Pausing: In the Debugger/Sources panel, click the pause button (usually looks like the pause button on a television remote control, ||) or press the keyboard equivalent. Keyboard equivalents are
Firefox & Chrome: F8
IE: Ctrl+Shift+B

(Updated 2020-03-30)
In Firefox 74 this option is in Options -> Privacy & Security -> Permissions
(Original reply)
Firefox has the option to prevent refresh natively, the option is in Advanced->General->Warn me when websites try to redirect or reload the page

The most popular solution for this problem is to trap the beforeunload event. The browser will ask the user for confirmation to leave the page. The code, in its simplest form, looks like this:
window.onbeforeunload = function() { return true }
You can enter this code in console. Alternately, you can simply paste the following URL in the browser address bar (console not required). You can even bookmark it.
javascript:window.onbeforeunload = function() { return true }
Be advised that modern browsers might chop off the javascript: part when you paste it inside the address bar; make sure you type it back.
To determine the cause of redirect in Firefox, try the following:
Open Web Developer Tools (CTRL + SHIFT + I), open "Toolbox Options" and check the "Enable persistent logs" option. This makes the logs persist across page loads (logs are cleared otherwise).
Now switch to "Network Monitor" tab.
Open the URL and let it refresh.
Inside the Network Monitor > Cause column you will find out why the page reloads.
The cause column is pretty ambiguous (Chrome does a much better job). However, if JavaScript was used to trigger page (re)load then it at least shows you the filename and line number of that script.

When the page is still loading, you can press the Esc key. While the page is still white, press it. When you stop the page from loading at this point, this usually stops all the auto loaded javascript. Any scripts that run on actions are usually not effected. Each page is different, try different timings.
When I use a site called NovelUpdates there is javascript that can make certain elements hidden, and when I press Esc on page load all the elements that would be hidden after page load are visible. Then when I click a button that would execute javascript that operates with no problems. NoScript isn't going to solve your issue I believe.
Another example of this are those websites with annoying boxes that pop out after 10 seconds that says you aren't a member and can't view any more of this site without logging in, like some news article websites.

What you could do is use the command exit(), which is the equivalent to die in php and simply stops the script.
If you don't know what's causing it and you don't want to look for the "bad boy", then you might as well stop the entire script at the very bottom of the page.

A bit confused about the "agenda" of a Chrome extension

So, I wrote a few extensions, most disposable and one hopefully viable.
I'm still a bit confused about the "agenda", of "schedule" or whatchacallit, i.e. the order in which things happen, and the places where they live.
For example, I am writing a new one that shall do the following :
a browser action presents the user with a menu of 3 items
two of those items trigger actions to be executed immediately, while the third lauches a process that is to run undercover for an extended period (namely polling a certain web page at an interval, said web page needing not to be loaded in any visible tab or window).
Naturally I'd be tempted to assume that the long-term is to live in the background.js.
Now, I understand that the pop-up menu is an HTML document in its own right, living its life in its own bubble. It shall disappear right after the user cliked on an item, thereby taking its context with it to its grave. Right now I'm at a bit of a loss trying to figure out how it can trigger a background process.
Notwithstanding, I don't quite grasp what brings the background.js to life, even less so when it is specified as non persistent as is recommended.
Naturally, I'll RTFM again, but if you fellows could dumb this down to my poor level of understanding, I'd be so happy ...

Maybe as you said, you would need to RTFM again..
Background Page runs in the extension process and exists for the lifetime of your extension, until your extension is removed or the browser process terminates.
While Event Page, what chrome has recommended to use, is loaded only when they are needed. Take a look at Lifetime part, the following are some example that will cause the event page to load:
The app or extension is first installed or is updated to a new version (in order to register for events).
The event page was listening for an event, and the event is dispatched.
A content script or other extension sends a message.
Another view in the extension (for example, a popup) calls runtime.getBackgroundPage.
As for your question, 'how it can trigger a background process', if there are no events to catch or message to pass, you can just call runtime.getBackgroundPage to load the event page.

How to not wait for something with Watir-Webdriver

So I'm writing a watir-webdriver script, and my app is using javascript to present a modal window that I want to interact with. When I click the element that presents the modal window, watir-webdriver just sits there until eventually it times out and i see a Timeout::Error on the console window. This is before attempting to interact with the new window at all. I'm assuming it's polling the DOM for some change and not getting it, how do I tell it to move on without waiting?

The answer ended up being, and then handling the necessary waiting manually
element.focus
element.send_keys :return

Ruby 1.9.3/ IE 9 - I had a click_no_wait error. Watir would not trigger a click on the Save button, which had to be followed by a click on a java popup 'OK' button that confirmed that the save button had saved the document correctly.
Using these two lines in place of the click_no_wait command gets the code working perfectly:
element.focus
element.send_keys :return
Thanks DVG. My code -
ie.button(:id, 'MainContent_B_Save').focus
ie.button(:id, 'MainContent_B_Save').send_keys :return
ie. javascript_dialog.button('OK').click

If this is a Alert, Confirm, or Alert type JS popup, see this answer: https://stackoverflow.com/a/8172888/409820