[Bug]: webContents.setWindowOpenHandler cannot set preload

[IrvingZhao]

Preflight Checklist

• I have read the Contributing Guidelines for this project.
• I agree to follow the Code of Conduct that this project adheres to.
• I have searched the issue tracker for a feature request that matches the one I want to file, without success.

Electron Version

16.0.2

What operating system are you using?

Windows

Operating System Version

Windows 11 21H2

What arch are you using?

x64

Last Known Working Electron version

No response

Expected Behavior

const conversationWindow = new BrowserWindow({
  webPreferences: {
    devTools: true,
    preload: path.resolve(__dirname, 'preload.js')
  }
})

  conversationWindow.webContents.setWindowOpenHandler(({ url }) => {
    if (url === 'about:blank') {
      return {
        action: 'allow',
        overrideBrowserWindowOptions: {
          frame: false,
          fullscreenable: false,
          backgroundColor: 'black',
          webPreferences: {
            preload: resolve(__dirname, 'preload2.js')
          }
        }
      }
    }
    return { action: 'deny' }
  })

In conversationWindow, use window.open('about:blank') to open a new window, execute preload2.js

Actual Behavior

it also execute preload.js

Testcase Gist URL

index.ts

Additional Information

No response

[thorsent]

I think that preloads will not run in window.open when contextIsolation=true for the parent window. This appears to be the case for both setWindowOpenHandler() as well as the deprecated new-window event (when setting newGuest).

I'm running Electron 13.6.1 . Since the OP is version 16.0.2, I think this is possibly a generalized problem.

@IrvingZhao can you try contextIsolation=false to see if the preload runs? (Perhaps it's defaulting to true in recent releases?)

[thorsent]

Same with -add-new-content (#26802). Preloads will only run when contextIsolation is false in the parent.

[thorsent]

This issue was mentioned in another thread: #16224 (comment)

[bastecklein]

I am having a similar issue. When my app was using Electron 14.x and I called window.open, the preload script was working on the child window (which is what I wanted). I have now upgraded to Electron v16.0.5 and the preload script is no longer loading on my child window, and I am not seeing anything in the changelogs to indicate why this is happening. I need to have contextisolation: true, and it worked fine before updating electron.

[t57ser]

This is happening because when navigating to about:blank the window will take over the webpreferences from the parent and it is not possible to change them.

electron/shell/renderer/electron_render_frame_observer.cc

Lines 84 to 86 in 94d4a07

	// When a child window is created with window.open, its WebPreferences will
	// be copied from its parent, and Chromium will intialize JS context in it
	// immediately.

Note that this is only happening for about:blank. See:

electron/shell/renderer/electron_render_frame_observer.cc

Lines 99 to 102 in 94d4a07

	// FIXME(zcbenz): Chromium does not do any browser side navigation for
	// window.open('about:blank'), so there is no way to override WebPreferences
	// of it. We should not delay Node.js initialization as there will be no
	// further loadings.

Other cases will work fine

[general-ice]

It looks like fixed. Latest electron 20.0.2

[github-actions]

This issue has been automatically marked as stale. If this issue is still affecting you, please leave any comment (for example, "bump"), and we'll keep it open. If you have any new additional information—in particular, if this is still reproducible in the latest version of Electron or in the beta—please include it with your comment!

[github-actions]

This issue has been closed due to inactivity, and will not be monitored. If this is a bug and you can reproduce this issue on a supported version of Electron please open a new issue and include instructions for reproducing the issue.