Undefinied button/ EUR button floating in my page

Technical Q&A

Topic summary

A developer is experiencing an issue with a floating button appearing on their webpage at animaniac.shop. The button displays reversed/mirrored text reading “UNDEFINED” (shown as “DENIFEDNU”) and “EUR”. The problem appears to be JavaScript-related based on the technical category and tags. No solutions or additional context have been provided yet, and the issue remains unresolved.

Summarized with AI on November 13. AI used: claude-sonnet-4-5-20250929.
1

https://www.animaniac.shop/

I have a floating button in my page saying UNDEFINED