feat: enable Array.fromAsync (#21048)

cli/main.rs

@@ -368,7 +368,8 @@ pub fn main() {
       // Using same default as VSCode:
       // https://github.com/microsoft/vscode/blob/48d4ba271686e8072fc6674137415bc80d936bc7/extensions/typescript-language-features/src/configuration/configuration.ts#L213-L214
       DenoSubcommand::Lsp => vec!["--max-old-space-size=3072".to_string()],
-      _ => vec![],
+      // TODO(bartlomieju): upstream this to `deno_core` crate
+      _ => vec!["--harmony-array-from-async".to_string()],
     };
     init_v8_flags(&default_v8_flags, &flags.v8_flags, get_v8_flags_from_env());
     deno_core::JsRuntime::init_platform(None);

cli/tests/unit/console_test.ts

@@ -500,6 +500,7 @@ Deno.test(function consoleTestStringifyFunctionWithProperties() {
   [isArray]: [Function: isArray] { [length]: 1, [name]: "isArray" },
   [from]: [Function: from] { [length]: 1, [name]: "from" },
   [of]: [Function: of] { [length]: 0, [name]: "of" },
+  [fromAsync]: [Function: fromAsync] { [length]: 1, [name]: "fromAsync" },
   [Symbol(Symbol.species)]: [Getter]
 }`,
   );

cli/tests/unit/globals_test.ts

@@ -153,3 +153,20 @@ Deno.test(async function promiseWithResolvers() {
     await assertRejects(() => promise, Error, "boom!");
   }
 });
+
+Deno.test(async function arrayFromAsync() {
+  // Taken from https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/fromAsync#examples
+  // Thank you.
+  const asyncIterable = (async function* () {
+    for (let i = 0; i < 5; i++) {
+      await new Promise((resolve) => setTimeout(resolve, 10 * i));
+      yield i;
+    }
+  })();
+
+  const a = await Array.fromAsync(asyncIterable);
+  assertEquals(a, [0, 1, 2, 3, 4]);
+
+  const b = await Array.fromAsync(new Map([[1, 2], [3, 4]]));
+  assertEquals(b, [[1, 2], [3, 4]]);
+});

cli/tsc/dts/lib.esnext.array.d.ts

@@ -291,3 +291,17 @@ interface BigUint64Array {
 
   with(index: number, value: number): BigUint64Array;
 }
+
+// NOTE(bartlomieju): taken from https://github.com/microsoft/TypeScript/issues/50803#issuecomment-1249030430
+// while we wait for these types to officially ship
+interface ArrayConstructor {
+  fromAsync<T>(
+      iterableOrArrayLike: AsyncIterable<T> | Iterable<T | Promise<T>> | ArrayLike<T | Promise<T>>,
+  ): Promise<T[]>;
+  
+  fromAsync<T, U>(
+      iterableOrArrayLike: AsyncIterable<T> | Iterable<T> | ArrayLike<T>, 
+      mapFn: (value: Awaited<T>) => U, 
+      thisArg?: any,
+  ): Promise<Awaited<U>[]>;
+}