# RSC-035: legacy JavaScript media type, how to fix it

Source: https://epubcc.com/epubcheck/rsc-035/ (updated 2026-11-04)

EPUBCheck RSC-035 is a usage message: “"…" is a legacy media type for JavaScript. Consider using 'text/javascript' instead.” A script uses a legacy media type for JavaScript, and EPUBCheck suggests text/javascript instead. It is a usage message, shown only with -u: the script still counts as JavaScript.

- Official message (EPUBCheck 5.4.0): "%1$s" is a legacy media type for JavaScript. Consider using 'text/javascript' instead.
- Default severity: Usage

## Typical causes

- Manifest items or script elements written with an older value such as application/javascript.
- Templates and tools that predate text/javascript becoming the recommended value.

## How to fix it

1. Find the media type named in the message.
2. Change it to text/javascript in the manifest item and in any script element type attribute.
3. Validate again with -u if you want a clean usage report.

## When it's not this

A script with a non-JavaScript media type is the error RSC-034.

## Sources

- EPUB 3.3, §3.2 Core media types: https://www.w3.org/TR/epub-33/#sec-core-media-types (read 2026-11-04)
- EPUBCheck 5.4.0 message texts (MessageBundle.properties, w3c/epubcheck on GitHub): https://github.com/w3c/epubcheck/blob/v5.4.0/src/main/resources/com/adobe/epubcheck/messages/MessageBundle.properties (read 2026-11-04)

Message text and severity: EPUBCheck (W3C, BSD-3-Clause). Explanation: EpubCC.