Ask HN: Does anyone have any good resources for learning Google Apps Script?

I've been trying to program a google sheet using Apps Script but most of the time, when I have an idea how to do something, it turns out that my idea is not something Apps Script can do and I have to implement it myself. For example, I thought there would be a function where you put in a number and it spits out a string of letters: 1 maps to "A", 27 maps to "AA". It turns out apps script has no such function and I had to implement it myself.

Apps Script has a huge API but I barely use it mostly because it doesn't really do anything I want to do. The fact that I'm not really using the API tells me I'm doing something wrong. Is there a book I was supposed to read or something? I already read the documentation google provides and it wasn't really helpful.