feat(types): IsEqual

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

src/types/__tests__/is-equal.spec-d.ts

@@ -0,0 +1,18 @@
+/**
+ * @file Type Tests - IsEqual
+ * @module tutils/types/tests/unit-d/IsEqual
+ */
+
+import type TestSubject from '../is-equal'
+
+describe('unit-d:types/IsEqual', () => {
+  it('should equal false A and B are not equal', () => {
+    expectTypeOf<TestSubject<0, 1>>().toEqualTypeOf<false>()
+    expectTypeOf<TestSubject<20, { limit: 20 }>>().toEqualTypeOf<false>()
+  })
+
+  it('should equal true if A and B are equal', () => {
+    expectTypeOf<TestSubject<13, 13>>().toEqualTypeOf<true>()
+    expectTypeOf<TestSubject<[1, 2], [1, 2]>>().toEqualTypeOf<true>()
+  })
+})

src/types/index.ts

@@ -46,6 +46,7 @@ export type { default as IsAny } from './is-any'
 export type { default as IsArray } from './is-array'
 export type { default as IsBigInt } from './is-big-int'
 export type { default as IsBoolean } from './is-boolean'
+export type { default as IsEqual } from './is-equal'
 export type { default as IsFunction } from './is-function'
 export type { default as IsJsonPrimitive } from './is-json-primitive'
 export type { default as IsNever } from './is-never'

src/types/is-equal.ts

@@ -0,0 +1,21 @@
+/**
+ * @file Type Definitions - IsEqual
+ * @module tutils/types/IsEqual
+ */
+
+/**
+ * Returns a boolean indicating if `A` and `B` are equal.
+ *
+ * @see https://github.com/microsoft/TypeScript/issues/27024#issuecomment-421529650
+ * @see https://stackoverflow.com/questions/68961864/how-does-the-equals-work-in-typescript/68963796#68963796
+ *
+ * @template A - First type to evaluate
+ * @template B - Second type to evaluate
+ */
+type IsEqual<A, B> = (<T>() => T extends A ? 1 : 2) extends <T>() => T extends B
+  ? 1
+  : 2
+  ? true
+  : false
+
+export type { IsEqual as default }