Migrate `String` to `StringPrototype`, `Number` to `NumberPrototype`, etc

[RyanCavanaugh]

Suggestion

🔍 Search Terms

string prototype object number stringprototype

✅ Viability 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, new syntax sugar for JS, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

⭐ Suggestion

We're always seeing people writing String, Number, Object, and so on, in places where they should be writing their primitive equivalents.

We should mark these as @deprecated so that they show up with strikethroughs in the editor, and make new global interfaces named e.g. StringPrototype so it's more clear what they're for.

/**
 * @deprecated Use `string` when working with strings, or use `StringPrototype` to declare new string methods
 */
interface String {

For back compat, possibly forever, we'll need to declare these as

interface StringPrototype extends String { }

so that existing references to String["charAt"] continue to work and so that other merges continue to function.

📃 Motivating Example

💻 Use Cases

• New users coming to TS

[RyanCavanaugh]

@DanielRosenwasser suggested also removing them from the global completion list, which also seems like a good idea

[MartinJohns]

For back compat, possibly forever

Consider removing it in the future, perhaps as part of 6.0? #54500

[fatcerberus]

I don't know if they can ever be removed completely, because otherwise what does new String("foo") return? (not that anyone should be doing that, but it's valid JS, so...)

[MartinJohns]

@fatcerberus Valid point, and I'd say: A compiler error. If people really want to do that, they can add the declaration themselves.

[RyanCavanaugh]

String the global variable stays put, of course. This is just about the interface