import fix / autocomplete requires type checking JS/JSX

[hedgepigdaniel]

Extracted issue from https://code.visualstudio.com/docs/nodejs/working-with-javascript#_type-checking-javascript

Auto complete of imports in JS/JSX files does not work properly unless type checking of JS/JSX files is explicitly enabled. This is counter intuitive, and forces the user to endure potentially unwanted type errors in order to have working autocomplete of imports.

It's extra confusing because the autocomplete does work for symbols exported from modules that are already imported (so it seems like it should work but is flaky). It took me a long time to find this problem.

[mjbvz]

Moving upstream for feedback

The reason we do this is that our IntelliSense can't understand certain JavaScript patterns. That makes it impossible to know if what our IntelliSense thinks is a missing symbol should be a real error (with a corresponding quick fix import) or if the symbol comes from somewhere else but our IntelliSense in not smart enough to pick it up (in which case an add missing import quick fix would get in the way and break the code). Requiring type checking is the current compromise

[RyanCavanaugh]

@mjbvz I think your rationale is correct here, but could see this as a potential configuration point. That said, auto-import is always a best-effort feature and we're never going to be able to get to 100% for all use cases.