The problem with @param is that it requires a binding name I ended up doing this instead: /** @typedef {{x: string}} FooArgs @typedef {{y: string}

The problem with @param is that it requires a binding name I ended up doing this instead: /** @typedef {{x: string}} FooArgs @typedef {{y: string}} FooResult @type {function(FooArgs): FooResult} */ export const foo = ({x}) => ({y: x}); It works, but the double curly feels a bit clunky. Compare to Flow: /*:: type FooArgs = {x: string}; type FooResult = {y: string}; type Foo = (FooArgs) => FooResult; */ export const foo /*: Foo */ = ({x}) => ({y: x}); In Flow, the declaration ends up looking essentially the same between comment syntax and non-comment syntax. With TS, RORO ends up looking like Flow (but with weirder indentation on large enough structs), whereas I'd prefer to express regular functions in terms of @callback, @param and @returns since that's more in line w/ the spirit of jsdoc. Not a huge deal, in any case, considering the upsides of comment syntax.