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Fix detecting an existing Map/Set

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This didn't affect compilation to CJS since that sets `exports.Map`
instead of creating a global.
This commit is contained in:
Eli Barzilay
2022-01-11 17:30:57 -05:00
parent b9efc3b614
commit 69277306c9
1 changed files with 10 additions and 4 deletions
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14
src/compiler/corePublic.ts
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@@ -114,16 +114,21 @@ namespace ts {
/* @internal */
namespace NativeCollections {
declare const Map: MapConstructor | undefined;
declare const Set: SetConstructor | undefined;
declare const self: any;
const globals = typeof globalThis !== "undefined" ? globalThis :
typeof global !== "undefined" ? global :
typeof self !== "undefined" ? self :
undefined;
/**
* Returns the native Map implementation if it is available and compatible (i.e. supports iteration).
*/
export function tryGetNativeMap(): MapConstructor | undefined {
// Internet Explorer's Map doesn't support iteration, so don't use it.
const gMap = globals?.Map;
// eslint-disable-next-line no-in-operator
return typeof Map !== "undefined" && "entries" in Map.prototype && new Map([[0, 0]]).size === 1 ? Map : undefined;
return typeof gMap !== "undefined" && "entries" in gMap.prototype && new gMap([[0, 0]]).size === 1 ? gMap : undefined;
}
/**
@@ -131,8 +136,9 @@ namespace ts {
*/
export function tryGetNativeSet(): SetConstructor | undefined {
// Internet Explorer's Set doesn't support iteration, so don't use it.
const gSet = globals?.Set;
// eslint-disable-next-line no-in-operator
return typeof Set !== "undefined" && "entries" in Set.prototype && new Set([0]).size === 1 ? Set : undefined;
return typeof gSet !== "undefined" && "entries" in gSet.prototype && new gSet([0]).size === 1 ? gSet : undefined;
}
}