The guide is written in JavaScript, wouldn’t it be better if it was written in TypeScript? Is it because that there might be users who might not know TypeScript?

I write TS at work so I’d be comfortable. But I don’t see how TS adds anything but complexity to those trying to learn. Additionally, there is an example in TS if someone was looking for specific guidance around TS. https://serverless-stack.com/examples/how-to-create-a-rest-api-in-typescript-with-serverless.html