Import Assertions

#40698

• Basic idea, adds some additional syntax to import statements.
• Doesn't affect us, we just need to "support" it by ignoring it.
• Allows a runtime to assert that some import shouldn't have any executable code.
• Looks like an object that you can stuff some options into.
• Do we need a global interface that declares the valid properties?
  • This would only affect dynamic import() right?
• Liked the idea of just supporting this and washing our hands of the host-specific details.
  • But seems like any host where this matters would have users savvy enough to add details here.
• Where do these live?
  • JSON is "universally accepted" in TC39, so maybe that goes in lib.es****.d.ts
  • CSS - maybe lib.dom.d.ts.
• How does this affect bundlers vs browser?
  • In theory shouldn't affect things.
  • This is contentious in the community.
  • Not sure what to do about this. 🤷‍♂️
• Feels incomplete to pass in non-string values,
• We'll start with the current changes, then follow-up with stricter types.

Type Display for Unresolved Types

#45893
#38836

• Hover over parameters: we can preserve the type
• Hovering over the type gives you type Thing = any
• Now find all references works at least for within the file.
• Dotted names are trickier.
  • What if you can resolve the namespaces but not the name itself.
• Shying away from the idea of displaying unresolved types differently - we try to preserve what you wrote in print-back.
• Currently only works for types - we could make it work for variables.
  • If we supported variables that are unresolved, it would light up misconfigured JS projects.
  • Deeper properties would be nice!
    • In fact, namespaces and property accesses are necessary to support namespace-style imports (i.e. import * as yadda).
    • Dotted type names, we intend to support.
    • Can speculate we try to create a symbol on the fly for a property.
      • Only aids find-all-refs.
      • Rename too.
        • Might not recommend doing that.
        • Not a safe refactoring.
    • How would you represent this?
      • Global map in checker?
• Doesn't only work in syntax-only mode - also is supported in full semantic mode where code is broken.