How to use SharePoint JSOM with Azure Functions

I like JSOM in SharePoint (at least more than alternatives). It gives the most complete client API to date (unlike REST) and adds automatic query batching on top of that - for free! One inconvenience though is that you cannot use same JSOM code both on client and on server - you have to switch to Powershell or C# CSOM (which often means rewriting same code in a different language)... But, no longer! …