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Superpowers for Dart. Collection of useful static extension methods.
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If you miss an extension, please open an issue or pull request


On this page you can find some of the extensions. Take a look at the docs to see all of them.

Getting started 🎉

Add the following to you pubspec.yaml and replace [version] with the latest version:

  dartx: ^[version]

After you import the library, you can use the extensions.

import 'package:dartx/dartx.dart';

var slice = [1, 2, 3, 4, 5].slice(1, -2); // [2, 3, 4]



Returns elements at indices between start (inclusive) and end (inclusive).

var list = [0, 1, 2, 3, 4, 5];
var last = list.slice(-1); // [5]
var lastHalf = list.slice(3); // [3, 4, 5]
var allButFirstAndLast = list.slice(1, -2); // [1, 2, 3, 4]

.sortedBy() & .thenBy()

Sort lists by multiple properties.

var dogs = [
  Dog(name: "Tom", age: 3),
  Dog(name: "Charlie", age: 7),
  Dog(name: "Bark", age: 1),
  Dog(name: "Cookie", age: 4),
  Dog(name: "Charlie", age: 2),

var sorted = dogs
    .sortedBy((dog) =>
    .thenByDescending((dog) => dog.age);
// Bark, Cookie, Charlie (7), Charlie (2), Tom


Get distinct elements from a list.

var list = ['this', 'is', 'a', 'test'];
var distinctByLength = list.distinctBy((it) => it.length); // ['this', 'is', 'a']


Get a new lazy Iterable of all elements from all collections in a collection.

var nestedList = [[1, 2, 3], [4, 5, 6]];
var flattened = nestedList.flatten(); // [1, 2, 3, 4, 5, 6]



Get a list of single character strings from a string. Supports emojis.

var chars = 'family👨‍👨‍👧‍👦'.chars; // ['f', 'a', 'm', 'i', 'l', 'y', '👨‍👨‍👧‍👦']


Returns true if this string is empty or consists solely of whitespace characters.

var notBlank = '   .'.isBlank; // false
var blank = '  '.isBlank; // true


Parses the string as an ineger or returns null if it is not a number.

var number = '12345'.toIntOrNull(); // 12345
var notANumber = '123-45'.toIntOrNull(); // null

Time utils

Dartx exports @jogboms great time.dart package so you can do the following:

int secondsInADay = 1.days.inSeconds;

Duration totalTime = [12.5.seconds, 101.milliseconds, 2.5.minutes].sum();

DateTime oneWeekLater = + 1.week;

Check out time.dart for more information and examples.



Ensures that this value lies in the specified range.

var numberInRange = 123.coerceIn(0, 1000); // 123
var numberOutOfRange = -123.coerceIn(0, 1000); // 0


Converts this value to binary form.



Creates a range between two ints (upwards, downwards and with custom steps)

// upwards with default step size 1
for (var i in 1.rangeTo(5)) {
  print(i); // 1, 2, 3, 4, 5
// downwards with custom step
for (var i in 10.rangeTo(2).step(2)) {
  print(i); // 10, 8, 6, 4, 2


.invoke() - DEPRECATED

Use call() instead. This is very useful for null checks.

var func = (String value) {

func?.call('hello world');

.partial(), .partial2() ...

Applies some of the required arguments to a function and returns a function which takes the remaining arguments.

void greet(String firstName, String lastName) {
  print('Hi $firstName $lastName!');

var greetStark = greet.partial('Stark');
greetStark('Sansa'); // Hi Sansa Stark!
greetStark('Tony'); // Hi Tony Stark!



Get the name and extension of a file.

var file = File('some/path/testFile.dart');
print(; // testFile.dart
print(file.nameWithoutExtension); // testFile


Append text to a file.

await File('someFile.json').appendText('{test: true}');


Checks if a file is inside a directory.

var dir = Directory('some/path');
File('some/path/file.dart').isWithin(dir); // true


Copyright 2019 Simon Leier

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
See the License for the specific language governing permissions and
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