Add import in the non-module description

[myogh]

• I think await doesn't play a role in deciding whether a JS file is a module or a script.

[orta]

I think this is previously accurate because only modules are allowed top level await but I think it's reasonable to add import to this list (instead of replacing await)

[myogh]

Thank you @orta, I was not aware of the "top level await" case. Thanks for mentioning it. Today I learned something new.

[jakebailey]

I think this one is tricky; having a top-level await doesn't cause TS to treat the file as a module. Instead, we use import/export or the moduleDetection setting to determine that, and then if we see a top-level await that shouldn't be there, we error.

But, I think this section is already awkward... it's not that the JavaScript spec says anything about these things, right?

[andrewbranch]

I’m not an expert on the ECMAScript grammar but I suspect the wording is a little weird here. The spec does distinguish between the grammars for script bodies and module bodies, and these three things are indeed relevant, but I think our wording probably implies the wrong causality. My understanding is that spec-compliant engines know ahead of time whether they should be parsing a script or a module (via <script type="module" in the browser, or file extension / package.json "type" in Node, for example), and that decision determines how the rest of the file is parsed, which makes import/export/TLA a syntax error in scripts. This is different from how TypeScript parses, where it has the ability to parse either one until an import or export is seen. That said, I don’t think it’s worth diving that far into the weeds here. This page will likely be replaced via microsoft/TypeScript#52593.