Why formatting is not preserved when copying data from SpreadJS to External Applications

When copying formatted data from SpreadJS and pasting it into external applications such as Confluence, JIRA, or Gmail, cell formatting (including background color, font color, and other styles) may not be preserved. However, when the same data is copied from Microsoft Excel or Google Sheets, the formatting is retained when pasted into these applications.

This difference can cause confusion when SpreadJS data appears visually correct within the spreadsheet but loses styling after being pasted into third-party editors.

This behavior occurs due to differences in how clipboard content is generated and interpreted.

When copying data from Excel, formatting is embedded directly into the HTML as inline style attributes. In contrast, SpreadJS applies formatting using CSS class definitions within the HTML. While both approaches are valid, applications such as Confluence and JIRA only recognize inline styles and ignore class-based styling when pasting content.

SpreadJS currently focuses on compatibility with Excel-style clipboard formats to ensure reliable copy-and-paste behavior between SpreadJS and Excel. Formatting preservation when pasting into third-party applications depends on how those applications process clipboard HTML and is not controlled by SpreadJS.