JSF UI Deprecation
This requires to have the JSF UI addon installed on your server that is deprecated since Nuxeo Platform LTS 2019.
Please refer to the Web UI documentation.
Getting a tag client id with JavaScript might be an issue. Here's how you can get your tag using DOM.
Some of this content is outdated and needs to be reviewed.
document.getElementById('div-id').childNodes[0]
TODO: there are better ways to handle this in JSF2
Related Documentation