Suggest argument names based on type definition of callback functions

Search Terms

callback, arguments, parameters, suggestion, auto correct

Suggestion

Let's say I have a type definition for my function like this:

function acceptsCallback(callback: (argumentNameThatIsVeryLong: string) => void) {}

When using it, that argumentNameThatIsVeryLong is a very good candidate for my argument name. I want to accept it but there is no way but typing it:

Use Cases

When users are extremely lazy this is very handy! ;) In all seriousness this can avoid bugs by suggesting the right argument name. For instance when req and res objects are misplaced in an Express middleware by mistake

Examples

https://www.typescriptlang.org/play?#code/GYVwdgxgLglg9mABAQwhApgBygZwMLIA2hARqgNYAUERpFAXIpcgE4DmIAtumFAHLJuAFQAWyKAEkcANXQsAngBkEbRjigsYYNgEpEAXgB8iAG5wYAEz0BvAL4Aoe6gzZ8tMhCqPv95ux32OkA

Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• 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 or tests are named. Start with the linked TypeScript Playground example and review how callback parameter suggestions currently behave in the editor. Done means argument names from a callback type definition are offered as suggestions without changing emitted JavaScript.