Web: Call preventDefault only when the plugin was enabled explicitly by setWebReturnValue

[saierd]

It was not possible to disable the behavior at the moment. Browsers understanding preventDefault() would always show the dialog as long as the plugin is enabled.

Broken in commit 166df017c8d050e5dcb58a92e189ce177dde6477.

Summary by CodeRabbit

• Bug Fixes
  • Fixed web platform window close and reload behavior to more precisely handle when default browser unload prevention should be applied, improving reliability of these operations.

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[coderabbitai[bot]]

Walkthrough

Modified the web beforeunload handler to conditionally invoke preventDefault() only when _returnValue is non-null, rather than unconditionally. The returnValue assignment logic remains unchanged, but the control flow for preventing default unload behavior is now gated behind the same null check.

Changes

Cohort / File(s)	Summary
Web beforeunload handler update lib/flutter_window_close_web.dart	Moved preventDefault() call inside the _returnValue null check to prevent the default unload behavior only when a return value is explicitly set.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

• Verify the conditional logic correctly gates preventDefault() behind the _returnValue check
• Confirm this change aligns with intended beforeunload behavior on web platforms
• Check for any test coverage updates needed for this control flow change

Poem

A rabbit hops through the web so bright, "Prevent less eagerly—only when right!" The unload now waits for the signal to go, A conditional dance, not a hasty preventDefault() show. 🐰✨

Pre-merge checks and finishing touches

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: calling preventDefault() conditionally based on setWebReturnValue enablement, which aligns with the changeset's control flow modification and the PR's objective to fix browser dialog behavior.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing touches

🧪 Generate unit tests (beta)

• [ ] Create PR with unit tests
• [ ] Post copyable unit tests in a comment

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[gemini-code-assist[bot]]

Summary of Changes

Hello @saierd, I'm Gemini Code Assist[^1]! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a bug in the web implementation of the window close plugin. Previously, the browser's default unload behavior was always prevented, leading to an inability to disable the 'stay on page' dialog. The change ensures that this prevention mechanism is only activated when the plugin has been explicitly configured to provide a return value for the unload event, restoring the intended control over the browser's behavior.

Highlights

• Conditional preventDefault() Call: The preventDefault() method on the BeforeUnloadEvent is now only invoked if a return value has been explicitly set via setWebReturnValue. This resolves an issue where the browser's 'stay on page' dialog would always appear, even when not intended.

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