Sample snippet for "Top 10 Array utility methods you should know (Dart) 🎯" article on Medium (Full solution)

top_10_array_utilities.dart

void main() {
  // forEach()
  var fruits = ['banana', 'pineapple', 'watermelon'];
  fruits.forEach((fruit) => print(fruit)); // => banana pineapple watermelon
  
  print('\n---\n');
  
  
  // map()
  var mappedFruits = fruits.map((fruit) => 'I love $fruit').toList();
  print(mappedFruits); // => ['I love banana', 'I love pineapple', 'I love watermelon']
  
  print('\n---\n');
  
  
  // contains()
  var numbers = [1, 3, 2, 5, 4];
  print(numbers.contains(2)); // => true
  
  print('\n---\n');
  
  
  // sort
  numbers.sort((num1, num2) => num1 - num2);
  print(numbers); // => [1, 2, 3, 4, 5]
  
  print('\n---\n');
  
  
  // reduce(), fold()
  var sum = numbers.reduce((current, next) => current + next);
  print(sum); // => 15
  
  const initialValue = 10;
  var sum2 = numbers.fold(initialValue, (current, next) => current + next);
  print(sum2); // => 25
  
  print('\n---\n');
	
  
  // every()
  List<Map<String, dynamic>> users = [
    { "name": 'Jane', "age": 18 },
    { "name": 'Jim', "age": 21 },
    { "name": 'Mary', "age": 23 },
  ];
  var is18AndOver = users.every((user) => user["age"] >= 18);
  print(is18AndOver); // => true
  
  var hasNamesWithJ = users.every((user) => user["name"].startsWith('J'));
  print(hasNamesWithJ); // => false
  
  print('\n---\n');
  
  
  // where(), firstWhere(), singleWhere()
  var over21s = users.where((user) => user["age"] > 21);
  print(over21s.length); // => 1
  
  var under18s = users.singleWhere((user) => user["age"] < 18, orElse: () => null);
  print(under18s); // => null
  
  var nameJ = users.firstWhere((user) => user["name"].startsWith('J'), orElse: () => null);
  print(nameJ); // => {name: Jane, age: 18}
  
  print('\n---\n');
  
  
  // take(), skip()
  var fiboNumbers = [1, 2, 3, 5, 8, 13, 21];
  print(fiboNumbers.take(3).toList()); // => [1, 2, 3]
  print(fiboNumbers.skip(5).toList()); // => [13, 21]
  print(fiboNumbers.take(3).skip(2).take(1).toList()); // => [3]
  
  print('\n---\n');
  
  
  // List.from()
  var clonedFiboNumbers = List.from(fiboNumbers);
  print(clonedFiboNumbers); // => [1, 2, 3, 5, 8, 13, 21]
  
  print('\n---\n');
  
  
  // expand()
  var pairs = [[1, 2], [3, 4]];
  var flattened = pairs.expand((pair) => pair).toList();
  print('Flattened result: $flattened'); // => [1, 2, 3, 4]
  
  var input = [1, 2, 3];
  var duplicated = input.expand((i) => [i, i]).toList();
  print(duplicated); // => [1, 1, 2, 2, 3, 3, 4, 4]
  
  print('\n---\n');
}