prefer_foreach

Use forEach to only apply a function to all the elements.

This rule is available as of Dart 2.0.

DO use forEach if you are only going to apply a function or a method to all the elements of an iterable.

Using forEach when you are only going to apply a function or method to all elements of an iterable is a good practice because it makes your code more terse.

BAD:

for (final key in map.keys.toList()) {
  map.remove(key);
}

GOOD:

map.keys.toList().forEach(map.remove);

NOTE: Replacing a for each statement with a forEach call may change the behavior in the case where there are side-effects on the iterable itself.

for (final v in myList) {
  foo().f(v); // This code invokes foo() many times.
}

myList.forEach(foo().f); // But this one invokes foo() just once.

To enable the prefer_foreach rule, add prefer_foreach under linter > rules in your analysis_options.yaml file:

linter:
  rules:
    - prefer_foreach

Unless stated otherwise, the documentation on this site reflects Dart 3.6.0. Page last updated on 2024-07-03. View source or report an issue.