I've been working on a little SPA that manipulates tabular data and allows the user to insert rows. This is exactly the API I've been using. Like a lot of other commenters it never occurred to me that people wouldn't know this API exists.

Aside: I started with Perl CGI scripts, then ColdFusion, and finally Classic ASP back in the 90s. I had a chuckle a couple years ago dealing with a younger developer who was shocked that and oldster like me was up on new-fangled SSR patterns.