Custom unsaved changes alert in filamentphp

First here is the code

//prevent-page-leave-alert.blade.php
@php
use Filament\Support\Facades\FilamentView;
@endphp

@if (FilamentView::hasSpaMode())
    @script
    <script>        
        shouldPreventNavigation = () => {
            if ($wire?.__instance?.effects?.redirect) {
                return
            }

            return $wire.preventPageLeave
        }

        const showUnsavedChangesAlert = () => {
            return confirm(@js(__('filament-panels::unsaved-changes-alert.body')))
        }

        document.addEventListener('livewire:navigate', (event) => {
            if (typeof @this !== 'undefined') {
                if (!shouldPreventNavigation()) {
                    return
                }

                if (showUnsavedChangesAlert()) {
                    return
                }

                event.preventDefault()
            }
        })

        window.addEventListener('beforeunload', (event) => {
            if (!shouldPreventNavigation()) {
                return
            }

            event.preventDefault()
            event.returnValue = true
        })
    </script> 
    @endscript
@else
    @script
    <script>        
        window.addEventListener('beforeunload', (event) => {
            if (!$wire.preventPageLeave) {
                return
            }

            event.preventDefault()
            event.returnValue = true
        })
    </script> 
    @endscript
@endif   

plus in your custom pages you need to use the following property

public bool $preventPageLeave = false;

it is false by default because we want the user to navigate freely until we have some action running that we want to keep, then we set the variable to true and the user will be prompted if they wanted to quit.

But why didn't we use HasUnsavedDataChangesAlert trait and the <x-filament-panels::page.unsaved-data-changes-alert /> blade component ?

Well, good question. it is because these two necessitate the page to have a $data property that not all custom pages would have.