Support labels in template string

🔍 Search Terms

template string label
template string name
interpolation label

✅ Viability Checklist

• 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 isn't a request to add a new utility type: https://github.com/microsoft/TypeScript/wiki/No-New-Utility-Types
• This feature would agree with the rest of our Design Goals: https://github.com/Microsoft/TypeScript/wiki/TypeScript-Design-Goals

⭐ Suggestion

The idea is to allow the addition of labels into a template literal.
This has no effect on the type itself in any way, the sole purpose is to give a better DX.

These labels would be shown by IntelliSense in order to provide the same experience as labels for the tuple labels.

📃 Motivating Example

// Template literal today
type Options = {
   name: `${string}/${string}`;
}

// With labels
type Options = {
   name: `${scope: string}/${baseName: string}`;
}

💻 Use Cases

This would offer a slightly better DX.
Right now you can document the parts of the template in a JSDoc comment, but the JSDoc is not preserve by IntelliSense in some cases.

Start with the motivating template-literal example and compare it with the existing tuple-label IntelliSense behavior referenced in the issue. The work is done when template literal labels improve IntelliSense documentation without changing the type or emitted JavaScript behavior.