[](https://github.com/leisim/dartx/actions) [](https://codecov.io/gh/leisim/dartx) [](https://pub.dev/packages/dartx) [](https://pub.dev/packages/flutterx)
_If you miss an extension, please open an issue or pull request_
### Resources:
- [Documentation](https://pub.dev/documentation/dartx/latest/dartx/dartx-library.html)
- [Pub Package](https://pub.dev/packages/dartx)
- [GitHub Repository](https://github.com/leisim/dartx)
On this page you can find some of the extensions. Take a look at the docs to see all of them.
## Getting started π
Add the following to your `pubspec.yaml`:
```dart
dependencies:
dartx: any
```
After you import the library, you can use the extensions.
```dart
import 'package:dartx/dartx.dart';
final slice = [1, 2, 3, 4, 5].slice(1, -2); // [2, 3, 4]
```
## Iterable
### .slice()
Returns elements at indices between `start` (inclusive) and `end` (inclusive).
```dart
final list = [0, 1, 2, 3, 4, 5];
final last = list.slice(-1); // [5]
final lastHalf = list.slice(3); // [3, 4, 5]
final allButFirstAndLast = list.slice(1, -2); // [1, 2, 3, 4]
```
### .sortedBy() & .thenBy()
Sort lists by multiple properties.
```dart
final 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),
];
final sorted = dogs
.sortedBy((dog) => dog.name)
.thenByDescending((dog) => dog.age);
// Bark, Cookie, Charlie (7), Charlie (2), Tom
```
### .distinctBy()
Get distinct elements from a list.
```dart
final list = ['this', 'is', 'a', 'test'];
final distinctByLength = list.distinctBy((it) => it.length); // ['this', 'is', 'a']
```
### .flatten()
Get a new lazy `Iterable` of all elements from all collections in a collection.
```dart
final nestedList = [[1, 2, 3], [4, 5, 6]];
final flattened = nestedList.flatten(); // [1, 2, 3, 4, 5, 6]
```
### .chunkWhile() & .splitWhen()
Chunk entries as long as two elements match a predicate:
```dart
final list = [1, 2, 4, 9, 10, 11, 12, 15, 16, 19, 20, 21];
final increasingSubSequences = list.chunkWhile((a, b) => a + 1 == b);
// increasingSubSequences = [[1, 2], [4], [9, 10, 11, 12], [15, 16], [19, 20, 21]]
```
`splitWhen` is the opposite of `chunkWhile` that starts a new chunk every time
the predicate _didn't_ match.
## int
### buildString()
Builds new string by populating newly created `StringBuffer` using provided `builderAction`
and then converting it to `String`.
```dart
final word = buildString((sb) {
for (var i = 0; i < 10; i++) {
sb.write(i);
}
});
// 0123456789
```
### .ordinal
Returns an ordinal number of `String` type for any integer
```dart
final a = 1.ordinal(); // 1st
final b = 108.ordinal(); // 108th
```
## String
### .capitalize
Returns a copy of the string having its first letter uppercased, or the original string, if it's empty or already starts with an upper case letter.
```dart
final word = 'abcd'.capitalize(); // Abcd
final anotherWord = 'Abcd'.capitalize(); // Abcd
```
### .decapitalize
Returns a copy of the string having its first letter lowercased, or the original string, if it's empty or already starts with a lower case letter.
```dart
final word = 'abcd'.decapitalize(); // abcd
final anotherWord = 'Abcd'.decapitalize(); // abcd
```
### .isAscii
Returns `true` if the string is ASCII encoded.
```dart
final isAscii = 'abc123 !,.~'.isAscii; // true
final isNotAscii = 'Β§3'.isAscii; // false
```
### .isBlank
Returns `true` if this string is empty or consists solely of whitespace characters.
```dart
final notBlank = ' .'.isBlank; // false
final blank = ' '.isBlank; // true
```
### .isDouble
Returns `true` if the string can be parsed as a double.
```dart
final a = ''.isDouble; // false
final b = 'a'.isDouble; // false
final c = '1'.isDouble; // true
final d = '1.0'.isDouble; // true
final e = '123456789.987654321'.isDouble; // true
final f = '1,000'.isDouble; // false
```
### .isInt
Returns `true` if the string can be parsed as an integer.
```dart
final a = ''.isInt; // false
final b = 'a'.isInt; // false
final c = '1'.isInt; // true
final d = '1.0'.isInt; // false
final e = '1,000'.isInt; // false
```
### .isLatin1
Returns `true` if the string is Latin 1 encoded.
```dart
final isLatin1 = 'Β§ΓΓΌ'.isLatin1; // true
final isNotLatin1 = 'Ε'.isLatin1; // false
```
### .isLowerCase
Returns `true` if the entire string is lower case.
```dart
final a = 'abc'.isLowerCase; // true
final b = 'abC'.isLowerCase; // false
final c = ' '.isLowerCase; // true
final d = ''.isLowerCase; // false
```
### .isNotBlank
Returns `true` if this string is not empty and contains characters except whitespace characters.
```dart
final blank = ' '.isNotBlank; // false
final notBlank = ' .'.isNotBlank; // true
```
### .isNullOrEmpty
Returns `true` if the String is either `null` or empty.
```dart
final isNull = null.isNullOrEmpty; // true
final isEmpty = ''.isNullOrEmpty; // true
final isBlank = ' '.isNullOrEmpty; // false
final isLineBreak = '\n'.isNullOrEmpty; // false
```
### .isNotNullOrEmpty
Returns `true` if the String is neither `null` nor empty.
```dart
final isNull = null.isNullOrEmpty; // true
final isEmpty = ''.isNullOrEmpty; // true
final isBlank = ' '.isNullOrEmpty; // false
final isLineBreak = '\n'.isNullOrEmpty; // false
```
### .isNullOrBlank
Returns `true` if the String is either `null` or blank.
```dart
final isNull = null.isNullOrBlank; // true
final isEmpty = ''.isNullOrBlank; // true
final isBlank = ' '.isNullOrBlank; // true
final isLineBreak = '\n'.isNullOrBlank; // true
final isFoo = ' foo '.isNullOrBlank; // false
```
### .isNotNullOrBlank
Returns `true` if the String is neither `null` nor blank.
```dart
final isNull = null.isNullOrBlank; // true
final isEmpty = ''.isNullOrBlank; // true
final isBlank = ' '.isNullOrBlank; // true
final isLineBreak = '\n'.isNullOrBlank; // true
final isFoo = ' foo '.isNullOrBlank; // true
```
### .isUpperCase
Returns `true` if the entire string is upper case.
```dart
final a = 'ABC'.isUpperCase; // true
final b = 'ABc'.isUpperCase; // false
final c = ' '.isUpperCase; // true
final d = ''.isUpperCase; // false
```
### .md5
Calculates the MD5 digest and returns the value as a string of hexadecimal digits.
```dart
final a = 'abc'.md5; // 900150983cd24fb0d6963f7d28e17f72
final b = 'ΰ΄βο€Ππ¨βπ¨βπ§βπ¦'.md5; // c7834eff7c967101cfb65b8f6d15ad46
```
### .urlEncode
Translates a string into application/x-www-form-urlencoded format using a specific encoding scheme.
```dart
const originalUrl = 'Hello Ladies + Gentlemen, a signed OAuth request!';
final encodedUrl = originalUrl.urlEncode;
// 'Hello%20Ladies%20+%20Gentlemen,%20a%20signed%20OAuth%20request!'
```
### .urlDecode
Decodes an application/x-www-form-urlencoded string using a specific encoding scheme.
```dart
const encodedUrl = 'Hello%20Ladies%20+%20Gentlemen,%20a%20signed%20OAuth%20request!';
final decodedUrl = encodingUrl.urlDecode;
// 'Hello Ladies + Gentlemen, a signed OAuth request!'
```
### .removePrefix(), .removeSuffix() and .removeSurrounding()
Remove a prefix, a suffix, or both from a given string:
```dart
final name = 'James Bond'.removePrefix('James '); // Bond
final milliseconds = '100ms'.removeSuffix('ms'); // 100
final text = 'Some HTML
' .removeSurrounding(prefix: '', suffix: '
'); // Some HTML ``` ### .reversed Returns a new string with characters in reversed order. ```dart final emptyString = ''.reversed; // '' final reversed = 'abcπ€'.reversed; // 'π€cba' ``` ### .slice() Returns a new substring containing all characters including indices [start] and [end]. If [end] is omitted, it is being set to `lastIndex`. ```dart final sliceOne = 'awesomeString'.slice(0,6)); // awesome final sliceTwo = 'awesomeString'.slice(7)); // String ``` ### .toDoubleOrNull() Parses the string as a `double` and returns the result or `null` if the String is not a valid representation of a number. ```dart final numOne = '1'.toDoubleOrNull(); // 1.0 final numTwo = '1.2'.toDoubleOrNull(); // 1.2 final blank = ''.toDoubleOrNull(); // null ``` ### .toInt() Parses the string as an integer and returns the result. The radix (base) thereby defaults to 10. Throws a `FormatException` if parsing fails. ```dart final a = '1'.toInt(); // 1 final b = '100'.toInt(radix: 2); // 4 final c = '100'.toInt(radix: 16); // 256 final d = '1.0'.toInt(); // throws FormatException ``` ### .toIntOrNull() Parses the string as an integer or returns `null` if it is not a number. ```dart final number = '12345'.toIntOrNull(); // 12345 final notANumber = '123-45'.toIntOrNull(); // null ``` ### .toUtf8() Converts String to UTF-8 encoding. ```dart final emptyString = ''.toUtf8(); // [] final hi = 'hi'.toUtf8(); // [104, 105] final emoji = 'π'.toUtf8(); // [240, 159, 152, 132] ``` ### .toUtf16() Converts String to UTF-16 encoding. ```dart final emptyString = ''.toUtf16(); // [] final hi = 'hi'.toUtf16(); // [104, 105] final emoji = 'π'.toUtf16(); // [55357, 56836] ``` ### .orEmpty() Returns the string if it is not `null`, or the empty string otherwise. ```dart String? nullableStr; final str = nullableStr.orEmpty(); // '' ``` ### .matches() Returns `true` if this char sequence matches the given regular expression. ```dart print('as'.matches(RegExp('^.s\$'))) // true print('mst'.matches(RegExp('^.s\$'))) // false ``` ### Time utils Dartx exports [@jogboms](https://github.com/jogboms) great [β° time.dart](https://github.com/jogboms/time.dart) package so you can do the following: ```dart int secondsInADay = 1.days.inSeconds; Duration totalTime = [12.5.seconds, 101.milliseconds, 2.5.minutes].sum(); DateTime oneWeekLater = DateTime.now() + 1.week; ``` Check out [β° time.dart](https://github.com/jogboms/time.dart) for more information and examples. ## num ### .coerceIn() Ensures that this value lies in the specified range. ```dart final numberInRange = 123.coerceIn(0, 1000); // 123 final numberOutOfRange = -123.coerceIn(0, 1000); // 0 ``` ### .toBytes() Converts this value to binary form. ### .toChar() Converts this value to character ```dart final character = 97.toChar(); // a ``` ## range ### rangeTo Creates a range between two ints (upwards, downwards and with custom steps) ```dart // upwards with default step size 1 for (final i in 1.rangeTo(5)) { print(i); // 1, 2, 3, 4, 5 } // downwards with custom step for (final i in 10.rangeTo(2).step(2)) { print(i); // 10, 8, 6, 4, 2 } ``` ## Function ### .partial(), .partial2() ... Applies some of the required arguments to a function and returns a function which takes the remaining arguments. ```dart void greet(String firstName, String lastName) { print('Hi $firstName $lastName!'); } final greetStark = greet.partial('Stark'); greetStark('Sansa'); // Hi Sansa Stark! greetStark('Tony'); // Hi Tony Stark! ``` ## File ### .name Get the name and extension of a file. ```dart final file = File('some/path/testFile.dart'); print(file.name); // testFile.dart print(file.nameWithoutExtension); // testFile ``` ### .appendText() Append text to a file. ```dart await File('someFile.json').appendText('{test: true}'); ``` ### .isWithin() Checks if a file is inside a directory. ```dart final dir = Directory('some/path'); File('some/path/file.dart').isWithin(dir); // true ``` ## Directory ### .file(String) References a file within a `Directory` ```dart Directory androidDir = Directory('flutter-app/android'); File manifestFile = androidDir.file("app/src/main/AndroidManifest.xml"); ``` References a directory within a `Directory` ### .directory(String) ```dart Directory androidDir = Directory('flutter-app/android'); Directory mainSrc = androidDir.directory("app/src/main"); ``` ### .contains(FileSystemEntity entity, {bool recursive = false}) Checks if a `Directory` contains a `FileSystemEntity`. This can be a `File` or a `Directory`. Use the `recursive` argument to include the subdirectories. ```dart final File someFile = File('someFile.txt'); final Directory someDir = Directory('some/dir'); final Directory parentDir = Directory('parent/dir'); parentDir.contains(someFile); parentDir.contains(someDir); parentDir.contains(someFile, recursive: true); parentDir.contains(someDir, recursive: true); ``` This is the `async` method, which returns a `FutureSome HTML
'.removeSurrounding(prefix: '', suffix: '
'); // Some HTML ``` - [PR-88](https://github.com/leisim/dartx/pull/88) New `List` extension `void swap(int, int)` which swaps the elements in the indices provided. ```dart final list = [1, 2, 3, 4]; list.swap(0, 2); // [3, 2, 1, 4] ``` - [PR-100](https://github.com/leisim/dartx/pull/100) Relax the upper version constraint of `collection` to support Flutter 1.20 (which uses `collection: 1.3.0-nullsafety`) - [PR-101](https://github.com/leisim/dartx/pull/101) Relax the upper version constraint of `crypto` ## 0.4.2 - Increase dependency range of `characters` to include `1.0.0` - Raise min sdk version to `2.6.0` to prevent pub publishing warning for pre-release versions ## 0.4.1 - [PR-84](https://github.com/leisim/dartx/pull/84) Increase `path` version range to be compatible with Flutter 1.17 - [PR-83](https://github.com/leisim/dartx/pull/83) Run tests on macOS ## 0.4.0 ### Iterable - [PR-41](https://github.com/leisim/dartx/pull/41) New `Iterable