hs cms theme preview does not respect JavaScript-based fields (fields.js)

[dawid-kokoszka]

CLI Version

8.5.0

Node.js Version

22.21.1

Operating System

macOS 26.4.1

Description

Write module and theme fields using JavaScript (https://developers.hubspot.com/docs/cms/start-building/building-blocks/fields/write-fields-using-javascript)

hs cms theme preview does not respect JavaScript-based fields (fields.js)

Primary problem:

The hs cms theme preview CLI command does not appear to process or convert JavaScript-based field definitions (fields.js / .cjs / .mjs). As a result, the local preview does not render fields correctly for themes/modules that use JS-authored fields.

Actual behavior:

The local preview does not render the fields defined in fields.js. It seems the command only reads fields.json and ignores JS field files.

Steps to Reproduce

1. Create a theme/module that defines fields usingfields.js(nofields.json).
2. Run hs cms theme preview .
3. Open the local preview URL

Expected Behavior

hs cms theme preview should evaluate fields.js (similar to how hs upload / hs watch do with --convertFields) and render the local preview using the resolved field values.

Screenshots

No response

Debug Output

No response

Additional Context

No response

[joe-yeager]

Thanks for the report @dawid-kokoszka - I will reach out to the CMS team about this and get back to you.