Intl.DisplayNames missing

[MichalBryxi]

Search Terms: Intl.DisplayNames, "Property 'DisplayNames' does not exist on type 'typeof Intl'."

Code

let languageNames = new Intl.DisplayNames(['en'], { type: 'language' });

Expected behavior: TS knows DisplayNames and does appropriate type checking.

Actual behavior: TS displays error: Property 'DisplayNames' does not exist on type 'typeof Intl'.

Playground Link: https://www.typescriptlang.org/play?ts=4.1.0-dev.20201030#code/DYUwLgBMCGB2DmBXa8QDloFsQGcIF4JYQB3CASVjGADoARASxwAcYBPDbHACgG0ByELH4BdADQQA3hDBtmIAFwR+MBMlT8IAXwCUAbgBQECEA
Related Issues: N/A

Respective MDN: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DisplayNames
Respective TC39: https://tc39.es/proposal-intl-displaynames/

[MartinJohns]

Type definitions for drafts are usually not added to the type definitions provided by TypeScript.

In the TypeScript-DOM-lib-generator project they list as a requirement for additions:

• Is the IDL source from WHATWG?
• • Are the additions available in at least two of Firefox, Safari and Chromium?
• Is the IDL source from W3C?
• • What stage of the W3C process is the proposal for these changes: We aim for Proposed recommendation, but can accept Candidate recommendation for stable looking proposals.
• • If it's at Working draft the additions available in all three of Firefox, Safari and Chromium

Neither Firefox nor Safari support this feature. There's no mention of TC39, but it's likely that the same principle applies.

---

You can use declaration merging to make the types available in your code base.

[typescript-bot]

This issue has been marked 'Working as Intended' and has seen no recent activity. It has been automatically closed for house-keeping purposes.

[TimvdLippe]

Can we reopen this issue for #44022 ?

[sroucheray]

It is now supported in all major browser versions https://caniuse.com/?search=Intl.DisplayNames and is referenced in ECMA402 https://tc39.es/ecma402/#intl-displaynames-objects. I think this might be time to reopen this issue.

[SchmidtDawid]

Why this is still causing problems? How to fix it?

[j-ulrich]

Should be fixed with TypeScript 4.5 according to PR #45647

[MichalBryxi]

TS playground v5.0.4 still says:

Property 'DisplayNames' does not exist on type 'typeof Intl'

[MartinJohns]

@MichalBryxi It works just fine in the Playground when you target an ES version that supports it.

[MichalBryxi]

Ah! So for future travelers: Minimum requirements that seem to work:

• TS v4.5.5 (supposedly v4.5 should be enough, but can't verify in the live playground)
• Target: ES2020