Hi
Even I have created a office js addin and I need to open existing xlsx/pptx document in excel/powerpoint. Office Js provides a way to open docx document with insertFile. Range.insertFile As you mentioned early on that there is no way to open xlsx/pptx file directly into excel or powerpoint using office js. I am thinking to use open xml sdk to fetch parts from xlsx or pptx doc and put them into empty xlsx or pptx document using setSelectedDataSync().
Is is possible using your open xml sdk?
Do you know any other way to load or open existing pptx/xlsx doc into office using office JS?
THanks in advance..