Describe the bug

This is only reproducible on Firefox and Safari.

If the activeElement is removed, the useActiveElement won't update the result to null. See video recorded on Firefox.

Currently, the useActiveElement is using blur event to track whether an element is unfocused. But per MDN doc:

Note however that blur is not fired when a focused element is removed from the document.

The blur is not fired when the activeElement is removed. This is discussed in Mozilla's bug tracker https://bugzilla.mozilla.org/show_bug.cgi?id=559561

One common use is the dialog. When the dialog is removed, the useActiveElement does not update the value accordingly.

Reproduction

https://stackblitz.com/edit/vitejs-vite-kmuiik?file=src%2FApp.vue

System Info

System:
    OS: macOS 14.4.1
    CPU: (10) arm64 Apple M1 Max
    Memory: 125.17 MB / 32.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 18.15.0 - ~/.nvm/versions/node/v18.15.0/bin/node
    npm: 9.5.0 - ~/.nvm/versions/node/v18.15.0/bin/npm
    pnpm: 8.15.3 - ~/Documents/Projects/JavaScript/VueJs/vueuse/node_modules/.bin/pnpm
  Browsers:
    Chrome: 124.0.6367.119
    Chrome Canary: 126.0.6459.0
    Safari: 17.4.1
  npmPackages:
    @vueuse/core: workspace:* => 10.9.0 
    @vueuse/integrations: workspace:* => 10.9.0 
    @vueuse/math: workspace:* => 10.9.0 
    @vueuse/rxjs: workspace:* => 10.9.0 
    @vueuse/shared: workspace:* => 10.9.0 
    vue: ^3.4.19 => 3.4.19

Used Package Manager

pnpm

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a VueUse issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to https://github.com/vuejs/core instead.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion.
• The provided reproduction is a minimal reproducible example of the bug.