Isn't this type already covered by https://github.com/sindresorhus/type-fest/blob/main/source/iterable-element.d.ts ?

Isn't this type already covered by main/source/iterable-element.d.ts ?

Hm, I'd assume so, but the tests for Exact fail if swapped to use IterableElement:

Any update here?

Is it really worth to import and use a custom type instead of just using a literal type offered by TypeScript?

- array[number]
+ ArrayElement<array>

The examples and tests don’t show why this would be beneficial.

Is it really worth to import and use a custom type instead of just using a literal type offered by TypeScript?

- array[number]
+ ArrayElement<array>

It's more of a syntactic and aesthetic improvement than a functional one. I do think it is a bit more verbose, but the type offered by TS can be hard to read/interpret at first glance:

type MyType = MyComplexType['property_1'][number]['subprop_1'] | null
// vs
type MyType = ArrayElement<MyComplexType['property_1']>['subprop_1'] | null

In your example it does not look like an advantage, it's hard to follow and does not match the order of the JS code.

              0             1            2        3 
              complexObject .property_1  [0]      .subprop_1

              0             1            2        3
type MyType = MyComplexType['property_1'][number]['subprop_1'] | null
// vs

              2           0             1              3
type MyType = ArrayElement<MyComplexType['property_1']>['subprop_1'] | null

I agree that ArrayElement<array> is more clear than array[number] to the untrained eye, but introducing this utility means that you'll inevitably end up with both on the codebase anyway, because it's not standard and people generally don't expect to use utilities to replace basic syntax.