feat(types): ExactOptionalPropertyTypes

Signed-off-by: Lexus Drumgold <[email protected]>

.eslintrc.cjs

@@ -14,7 +14,11 @@ const config = {
   overrides: [
     ...require('./.eslintrc.base.cjs').overrides,
     {
-      files: ['src/types/built-in.ts', 'src/types/overwrite.ts'],
+      files: [
+        'src/types/built-in.ts',
+        'src/types/exact-optional-property-types.ts',
+        'src/types/overwrite.ts'
+      ],
       rules: {
         '@typescript-eslint/ban-types': 0
       }

src/types/exact-optional-property-types.ts

@@ -0,0 +1,21 @@
+/**
+ * @file Type Definitions - ExactOptionalPropertyTypes
+ * @module tutils/types/ExactOptionalPropertyTypes
+ */
+
+import type ObjectPlain from './object-plain'
+
+/**
+ * Removes `undefined` from optional properties.
+ *
+ * This is a workaround for [`Microsoft/TypeScript#46969`][1].
+ *
+ * [1]: https://github.com/Microsoft/TypeScript/issues/46969
+ */
+type ExactOptionalPropertyTypes<T extends ObjectPlain> = {
+  [K in keyof T]: Exclude<T[K], undefined> extends never
+    ? T[K]
+    : Exclude<T[K], undefined>
+} & {}
+
+export type { ExactOptionalPropertyTypes as default }

src/types/index.ts

@@ -12,6 +12,10 @@ export type { default as Constructor } from './constructor'
 export type { default as ContinuousValue } from './continuous-value'
 export type { default as EmptyString } from './empty-string'
 export type { default as EmptyValue } from './empty-value'
+// prettier-ignore
+export type {
+  default as ExactOptionalPropertyTypes
+} from './exact-optional-property-types'
 export type { default as FIXME } from './fixme'
 export type { default as IndexSignature } from './index-signature'
 export type { default as Join } from './join'