> I don't know what you mean here, but it is certainly possible for TypeScript code to use JavaScript libraries and vice versa, which is presumably what most people mean by "TypeScript interops with JavaScript".
Ah, I can see what you/they mean by that. The point I was trying to get across was: TypeScript doesn't exist when code is actually executing (which is what I think of as interop - it's happening at execution time.) At execution time - it's all just JavaScript.
I have found (working in a TypeScript team currently) that this fact is ignored, primarily by people who "look down" on JavaScript, but it is a VERY important point to remember when you are writing TypeScript, mostly because it's important to remember there is only compile time type checking not run time.
Heh, yes - as soon as I posted I realised that was silly. The word "always" is almost "always" incorrect! I should have said: "It usually transpiles to JavaScript and usually runs as JavaScript"
> The Million Dollar Mistake is having unchecked nulls; TypeScript supports checked nulls so it's not an issue. TypeScript's nulls are much more similar to Maybe/Option than unchecked nulls
Good point in theory but my practical experience hasn't borne this out. That is because TypeScript is an "optionally typed" language and it hasn't been true in practice because of excessive use of explicit or implicit "any"s.
> and in some scenarios transpile down to JavaScript
It always transpiles to JavaScript and always runs as JavaScript. There is no such thing as a TypeScript runtime engine.
TypeScript is a superset of JavaScript. Therefore the OP's point is still valid. Any "mistakes" JavaScript might have made about having null AND undefined are also issues for TypeScript.
interesting thanks for the heads up - my assumption is though that this is just a wrapper over a V8 engine with typescript compilation on the fly?
Does that make it a TypeScript runtime or not?