Currently I have an World Add-in which can be used on Excel too by adding Excel as a Host but I just want to know if the same add-in supporting Word and Excel as hosts can be used to create excel functions too.
I've tried to make changes to manifest and webpack.config.js but they don't seem to work. Is it possible to have a single office add-in supporting Word and Excel with some common features and Custom Excel Functions
Is it possible to have a single office add-in supporting Word and Excel with some common features and Custom Excel Functions
Yes, it is possible to support multiple host applications by a single Office web add-in. You just need to make the required adjustments in the manifest file. But please remember that host-specific features make sense only if the add-in is being run in the host that provides such features (like Excel with custom functions).
By default, an add-in is installable in all Office applications supported by the specified add-in type (that is, Mail, Task pane, or Content). For example, a task pane add-in is installable by default on Access, Excel, OneNote, PowerPoint, Project, and Word.
To ensure that your add-in is installable in a subset of Office applications, use the Hosts and Host elements in the manifest.
It isn't possible for an add-in manifest to apply to more than one type: Mail, Task pane, or Content. This means that if you want your add-in to be installable on Outlook and on one of the other Office applications, you must create two add-ins, one with a Mail type manifest and the other with a Task pane or Content type manifest.
Read more about that in the Specify Office applications and API requirements article.