Fill, a common JavaScript function, now let us implement it with types.
Fill<T, N, Start?, End?>, as you can see,Fill accepts four types of parameters, of which T and N are required parameters, and Start and End are optional parameters.
The requirements for these parameters are: T must be a tuple, N can be any type of value, Start and End must be integers greater than or equal to 0.
type exp = Fill<[1, 2, 3], 0> // expected to be [0, 0, 0]
In order to simulate the real function, the test may contain some boundary conditions, I hope you can enjoy it :)
import type { Equal, Expect } from '@type-challenges/utils'
type cases = [
Expect<Equal<Fill<[], 0>, []>>,
Expect<Equal<Fill<[], 0, 0, 3>, []>>,
Expect<Equal<Fill<[1, 2, 3], 0, 0, 0>, [1, 2, 3]>>,
Expect<Equal<Fill<[1, 2, 3], 0, 2, 2>, [1, 2, 3]>>,
Expect<Equal<Fill<[1, 2, 3], 0>, [0, 0, 0]>>,
Expect<Equal<Fill<[1, 2, 3], true>, [true, true, true]>>,
Expect<Equal<Fill<[1, 2, 3], true, 0, 1>, [true, 2, 3]>>,
Expect<Equal<Fill<[1, 2, 3], true, 1, 3>, [1, true, true]>>,
Expect<Equal<Fill<[1, 2, 3], true, 10, 0>, [1, 2, 3]>>,
Expect<Equal<Fill<[1, 2, 3], true, 10, 20>, [1, 2, 3]>>,
Expect<Equal<Fill<[1, 2, 3], true, 0, 10>, [true, true, true]>>,
]