mergeDeep: support arrayMergeMode option #1198
Description
Just discovered Remeda after looking for an alternative to es-toolkit which has some type issues in some cases due to its loose types.
One thing I miss from es-toolkit is its mergeWith utility. Specifically, I use it to deeply merge two objects while concatenating arrays:
import { mergeWith } from "es-toolkit"
mergeWith(target, source, (objValue: unknown, srcValue: unknown) =>
Array.isArray(objValue) ? objValue.concat(srcValue) : undefined,
)The MergeDeep type from type-fest that mergeDeep already returns supports this kind of thing:
MergeDeep<Destination, Source, { arrayMergeMode: "spread" }>.
So my suggestion would be something like mergeDeepConcat instead of an actual mergeWith function, because I'm not sure how you'd be able to handle types correctly in the latter case.
function mergeDeepConcat<Destination extends object, Source extends object>(destination: Destination, source: Source):
MergeDeep<Destination, Source, { arrayMergeMode: "spread" }>