3 ms·

According to https://github.com/microsoft/TypeScript/wiki/Performance#preferring-base-types-over-unions https://github.com/microsoft/TypeScript/wiki/Performance

According to https://github.com/microsoft/TypeScript/wiki/Performance#preferring-base-types-over-unions https://github.com/microsoft/TypeScript/wiki/Performance#pre... using union types in your example vs interfaces like #6 is bad for compilation performance.

bryzio 6y ago
As the docs mention, the effect is only material when there's a non-trivial number of union elements. For unions containing only a handful of elements the effect is inconsequential.