Webview using deprecated `on_result`

[kattni]

Describe the bug

When running the Webview example, when clicking on one of the js buttons, the following deprecation warning is thrown:

webview.py:193: DeprecationWarning: Synchronous `on_result` handlers have been deprecated; use `await` on the asynchronous result
  result = JavaScriptResult(on_result=on_result)

Steps to reproduce

1. Run the webview example code.
2. Click on "good js" or "bad js".
3. Check console output.

Expected behavior

Presumably that the error is not present.

Screenshots

No response

Environment

• Operating System: macOS 15.5
• Python version: 3.13
• Software versions:
  • Toga: 0.5.2.dev139+gef79e0427.d20250705

Logs

Additional context

No response

[freakboy3742]

Good catch.

The fix here is convert the synchronous on_bad_js handler into an asynchronous handler. As the error message suggests - make on_bad_js an async def method, and instead of passing in an on_result completion handler, remove the on_result argument, await the call to evaluate_javascript, and make the contents of the previous on_result handler the commands that are invoked after the await call.

There's likely some other tweaks and cleanups that will be needed, but they should become apparent once that conversion has been done.

[snowkoli]

I will work on this, europython 2025