Office Add-in with method that requires Excel JS API 1.9 runs on Office 2016. How is this possible?

Question

I have made an Office JS Addin that makes use of

copyFrom(sourceRange: Range | RangeAreas | string, copyType?: Excel.RangeCopyType, skipBlanks?: boolean, transpose?: boolean): void;

This method requires Excel JS API 1.9 so it is supported on Office 365 according to documentation. Also, my Addin makes use of other methods that require Excel JS API > 1.1. I am wondering how it is possible for my Addin to be fully functional in Office 2016 which supports only up to Excel JS API 1.1 . Keep in mind that I have no runtime checks using the isSetSupported() method. I would expect my Addin to be functional only on Office 365. Does it make sense to you? Am I missing something?

Answer 1

Builds 16.0.13426.XXXXX is actually a Monthly Subscription build. At the time of this writing is actually the latest publicly available Office version in Production. Hence 1.9 will be supported along with the copyFrom API.