valueOf method

V valueOf(
  1. K key, {
  2. required V initialValue,
})

Returns the value of the given key, if it exists, and adds it if it doesn't If the the key does not exist, the given initialValue is added and returned

final animalRatings = { "aardvark": 1, "baboon": 2 };
final aardvarkRating = animalRatings.valueOf("aardvark", initialValue: 0); // Returns existing value of 1
final baboonRating = animalRatings.valueOf("baboon", initialValue: 2); // Adds baboon and returns the value of 2

Implementation

V valueOf(K key, {required V initialValue}) {
  if (containsKey(key)) return this[key]!;
  this[key] = initialValue;
  return initialValue;
}