Google AppScript in Gsuite, what is the equivalent in MS O365 ?

[Debayan]

Hi O365 Experts,
Would like to know what is the similar feature in O365 for AppScript in google (Google appsScript).

Using Appscript with Gsuite Sheets users can write custom functions for other Google services.
https://developers.google.com/apps-script/guides/sheets

Would like to know if i have to migrate users from GSuite environment to O365 which will be the similar compared to Appscript.

Ref : https://www.youtube.com/watch?v=_APsUaXd980

[#2]

Graph API: https://docs.microsoft.com/en-us/graph/api/resources/excel?view=graph-rest-1.0

[#3]

@Vasil Michev 

Hi Vasil Thanks, do you have any video tutorial or demo link, compact one ?
Also wanted to see how we can write functions in side Web Excel /one drive.

[#4]

Did you try reviewing the links on the left nav pane of the documentation?

[#5]

@Vasil Michev 

Yes, the documentation is too much less visuals.