feat(question): add #17908 - Union from values in an object

questions/17908-medium-union-from-values-in-an-object/README.md

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+Create a generalizable type UnionOfArrayValuesInObject that can be used to create a union type of all the values from all the array values inside an object that contains object keys and arrays as the objects. 
+
+The task is solvable without using utility types.
+
+```ts
+const object1WithObjectArrays= {
+ key: ['one', 'two', 'three']
+} as const
+
+const object2WithObjectArrays= {
+ key: [1, 2, 3]
+} as const
+
+const AllMeasurementUnits = {
+ weight: ['g', 'kg', 'pound'],
+ length: ['cm', 'm', 'inch']
+} as const
+
+type UnionOfArrayValuesInObject<T> = any
+
+const oneString: UnionOfArrayValuesInObject<typeof object1WithObjectArrays> = 'one' //should be a valid type
+const fourString: UnionOfArrayValuesInObject<typeof object2WithObjectArrays> = 'four' //shouldn't be a valid type
+
+const oneNumber: UnionOfArrayValuesInObject<typeof object2WithObjectArrays> = 1 //should be a valid type
+
+const grams: UnionOfArrayValuesInObject<typeof AllMeasurementUnits> = 'g' //should be a valid type
+const ounce: UnionOfArrayValuesInObject<typeof AllMeasurementUnits> = 'ounce' //shouldn't be a valid type
+```

questions/17908-medium-union-from-values-in-an-object/info.yml

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+difficulty: medium
+title: Union from values in an object
+tags: union, array, object, object-keys, const assertions
+author:
+ github: koodiohto
+ name: Ohto Rainio
+

questions/17908-medium-union-from-values-in-an-object/template.ts

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+const object1WithObjectArrays= {
+ key: ['one', 'two', 'three']
+} as const
+
+const object2WithObjectArrays= {
+ key: [1, 2, 3]
+} as const
+
+const AllMeasurementUnits = {
+ weight: ['g', 'kg', 'pound'],
+ length: ['cm', 'm', 'inch']
+} as const
+
+type UnionOfArrayValuesInObject<T> = any
+
+const oneString: UnionOfArrayValuesInObject<typeof object1WithObjectArrays> = 'one' //should be a valid type
+const oneNumber: UnionOfArrayValuesInObject<typeof object2WithObjectArrays> = 1 //should be a valid type
+const grams: UnionOfArrayValuesInObject<typeof AllMeasurementUnits> = 'g' //should be a valid type

questions/17908-medium-union-from-values-in-an-object/test-cases.ts

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+import type { Equal, Expect } from '@type-challenges/utils'
+
+type cases = [
+ Expect<Equal<UnionOfArrayValuesInObject<typeof object1WithObjectArrays>, 'one' | 'two' | 'three'>>,
+ Expect<Equal<UnionOfArrayValuesInObject<typeof object2WithObjectArrays>, 1 | 2 | 3 >>,
+ Expect<Equal<UnionOfArrayValuesInObject<typeof AllMeasurementUnits>, 'g' | 'kg' | 'pound' | 'cm' | 'm' | 'inch'>>,
+]