avoid-map-keys-contains

effort: 2m

has IDE fix

has auto-fix

starter+

Warns when Map's .keys.contains is used instead of containsKey.

.keys.contains is 6000 times slower than containsKey and should be avoided.

❌ Bad:

void main() {
  final map = {'hello': 'world'};

  // LINT: Avoid '.keys.contains'. Try using '.containsKey' instead.
  map.keys.contains('hello');
}

✅ Good:

void main() {
  final map = {'hello': 'world'};

  map.containsKey('hello'); // Correct, uses 'containsKey'
}