You can solve this problem with vanilla-Js:
Unload Basics
If you want to prompt or warn your user that they're going to close your page, you need to add code that sets .returnValue
on a beforeunload
event:
window.addEventListener('beforeunload', (event) => {
event.returnValue = `Are you sure you want to leave?`;
});
There's two things to remember.
Most modern browsers (Chrome 51+, Safari 9.1+ etc) will ignore what you say and just present a generic message. This prevents webpage authors from writing egregious messages, e.g., "Closing this tab will make your computer EXPLODE! ".
Showing a prompt isn't guaranteed. Just like playing audio on the web, browsers can ignore your request if a user hasn't interacted with your page. As a user, imagine opening and closing a tab that you never switch to—the background tab should not be able to prompt you that it's closing.
Optionally Show
You can add a simple condition to control whether to prompt your user by checking something within the event handler. This is fairly basic good practice, and could work well if you're just trying to warn a user that they've not finished filling out a single static form. For example:
let formChanged = false;
myForm.addEventListener('change', () => formChanged = true);
window.addEventListener('beforeunload', (event) => {
if (formChanged) {
event.returnValue = 'You have unfinished changes!';
}
});
But if your webpage or webapp is reasonably complex, these kinds of checks can get unwieldy. Sure, you can add more and more checks, but a good abstraction layer can help you and have other benefits—which I'll get to later. ♀️
Promises
So, let's build an abstraction layer around the Promise
object, which represents the future result of work- like a response from a network fetch()
.
The traditional way folks are taught promises is to think of them as a single operation, perhaps requiring several steps- fetch from the server, update the DOM, save to a database. However, by sharing the Promise
, other code can leverage it to watch when it's finished.
Pending Work
Here's an example of keeping track of pending work. By calling addToPendingWork
with a Promise
—for example, one returned from fetch()
—we'll control whether to warn the user that they're going to unload your page.
const pendingOps = new Set();
window.addEventListener('beforeunload', (event) => {
if (pendingOps.size) {
event.returnValue = 'There is pending work. Sure you want to leave?';
}
});
function addToPendingWork(promise) {
pendingOps.add(promise);
const cleanup = () => pendingOps.delete(promise);
promise.then(cleanup).catch(cleanup);
}
Now, all you need to do is call addToPendingWork(p)
on a promise, maybe one returned from fetch()
. This works well for network operations and such- they naturally return a Promise
because you're blocked on something outside the webpage's control.
more detail can view in this url:
https://dev.to/chromiumdev/sure-you-want-to-leavebrowser-beforeunload-event-4eg5
Hope that can solve your problem.