insertWith package:mono-traversable

Insert a key-value pair into a map. Inserts the value directly if the key does not exist in the map. Otherwise, apply a supplied function that accepts the new value and the previous value and insert that result into the map.

Insert a key-value pair into a map. Inserts the value directly if the key does not exist in the map. Otherwise, apply a supplied function that accepts the key, the new value, and the previous value and insert that result into the map.