Support Closure Compiler-style @typedef

Search Terms

• Closure Compiler typedef

Suggestion

With Closure Compiler-style JSDoc, you name an @typedef type definition by introducing a var in the next statement:

/** @typedef {(string|number)} */
var NumberLike;

TypeScript doesn't recognize this construct. Instead, it wants you to write:

/** @typedef {(string|number)} NumberLike */

Use Cases

Migrating code written for use with Google's Closure Compiler over to TypeScript.

Examples

See above. My proposal is that, when prefixed with an @typedef with only a type (and no name), a variable definition would create a symbol in the type namespace in addition to the value namespace.

Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
  → If the variable has the same name as an existing type, this would create a break. But this would indicate an issue if the two types disagreed.
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

No implementation files, tests, or entry points are named. Start by tracing how TypeScript handles Closure-style JSDoc @typedef declarations, then compare the existing named form with the proposed variable-based form; done means the example creates the requested type symbol without changing emitted JavaScript.