Add refactoring action to annotate a variable or a function signature component with its inferred type

Hi, I’m using latest stable VSCode / latest nightly TS and I’m not sure if codefixes and refactorings have been implemented there yet, in any case, having a refactoring option to take any variable which receives an implicit inferred type, say, through a function call:

function test(): number[] {
  // ...
}

let x = test(); 

And being able to right-click x and invoke an action like Annotate with inferred type (or Extract inferred type), such that the resulting statement would look like:

let x: number[] = test();

could be very useful!

[aluanhaddad]

I would certainly appreciate having the opposite capability.

[rotemdan]

Also, being able to annotate functions or methods with their inferred return types, e.g.

function test() {
  return [1,2,3,4];
}

Right click test, select Annotate with inferred return type, leading to:

function test(): number[] {
  return [1,2,3,4];
}

Would also be very useful. I do that a lot, sometimes to have it visibly documented, or make sure that the return type is stabilized such that further changes to the body of the function that break it would be detected.

There are also cases where callback’s signature types are inferred like

function example(f: (a: number, b: string) => boolean) {
}

example((x, y) => {
})

Where right clicking x, y or => and choosing Annotate with inferred type/Annotate with inferred return type or even combined to a single action like Annotate with inferred signature (maybe when, say, the arrow is right clicked for an anonymous function) could also be useful.