Missing ListFormat types?

[chasm]

I can do this in the REPL and it works:

new Intl.ListFormat("en", {
    style: "long",
    type: "conjunction",
}).format(['red', 'green', 'blue']) // returns "red, green, and blue"

But if I put the same code in my Deno application, I get:

[ERROR]: Property 'ListFormat' does not exist on type 'typeof Intl'.

when I try to bundle it.

[kitsonk]

Can you provide a full reproduction and include the output of deno --version.

[chasm]

This is literally my entire code in a file called mod.ts:

const ListFormatter = new Intl.ListFormat("en", {
	style: "long",
	type: "conjunction",
});

console.log(ListFormatter.format(["apples", "pears", "peaches", "plums"]));

Here's what happens when I run it:

[listFormat] deno run ./mod.ts
Check file:///Users/chasm/Workspace/listFormat/mod.ts
error: TS2339 [ERROR]: Property 'ListFormat' does not exist on type 'typeof Intl'.
const ListFormatter = new Intl.ListFormat("en", {
                               ~~~~~~~~~~
    at file:///Users/chasm/Workspace/listFormat/mod.ts:1:32

Here is the output of deno --version:

[listFormat] deno --version
deno 1.17.1 (release, x86_64-apple-darwin)
v8 9.7.106.15
typescript 4.5.2

Here is what happens when I do the same thing in the REPL:

[listFormat] deno
Deno 1.17.1
exit using ctrl+d or close()
> const ListFormatter = new Intl.ListFormat("en", {
	style: "long",
	type: "conjunction",
});

console.log(ListFormatter.format(["apples", "pears", "peaches", "plums"]));
apples, pears, peaches, and plums
undefined
>

As the output is correct, clearly Intl.ListFormat does exist in Deno. The problem appears only when it is type checked.

Ideas? Is there a workaround?

[crowlKats]

This is an issue with typescript itself: microsoft/TypeScript#46907

[chasm]

Thanks. I'll check on it there.

[andreubotella]

We have added built-in APIs to the Typescript definition files when a version of Deno would ship with those APIs but Typescript didn't support them yet (see #11443, for example). The differences here is that Intl.ListFormat shipped a while ago (browser-compat-data lists it as shipping in Chrome 72) and apparently no one noticed until now, and that there isn't yet even a PR for adding the definitions in Typescript. But I don't see why we couldn't open a PR to Typescript and float the patch in Deno while it gets reviewed upstream.

[chasm]

That would be awesome...