Search Terms

• Intl
• Intl.NumberFormat
• Intl.NumberFormat.formatToParts
• formatToParts

(searched wiki, FAQ, issues, and the code)

Suggestion

I'd like to add Intl.NumberFormat.formatToParts method and its return types as stated here at TC39. The proposal is on stage 4 and describes the formatToParts for Intl.NumberFormat and Intl. DateTimeFormat. The last one already got implemented by @donaldpipowitch in #15369, but for Intl.NumberFormats types are still missing.
The code would be pretty close to the DateTimeFormat implementation except for the *FormatPartTypes following ECMA402

Use Cases

For use cases and examples please see TC39/Intl formatToParts.

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. new expression-level syntax)

Are you open for a pull request?
And would you prefer it to extend either

• the existing one for Intl.DateTime in lib/es2017.intl.d.ts
• the base interface of Intl.NumberFormat in lib/es5.d.ts:4060?