JavaScript expressions used with the Export to HTML feature can refer to columns in the table and invoke computed items. They can also refer to any JavaScript class like Math and String. Those computed items which do not have direct equivalent among the built-in Excel functions are simulated by custom VB functions. See Formula Mappings for computed item to Excel built-in function mappings.
If the expression refers to a JavaScript class not supported by the Export feature, #NAME? is displayed in the Excel cell (and as a valid value in the web browser) and the Error Office html tag attribute is used. In addition, a comment is added to the cell explaining the error. In Excel, this comment is displayed near the cell where the error occurred. In the browser, the comment is displayed when you hover the mouse pointer over a cell with a small red-colored corner.