Linq for JavaScript

From

Thank you

Install

npm install linq-to-javascript --save

Usage

import

const Linq = require('linq-to-javascript');

1. all

const numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];

const rst = new Linq(numbers).all(x => x < 5); // => false

2. any

const numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];

const rst = new Linq(numbers).any(x => x < 5); // => true

3. count

const strArr = ['正一郎', '清次郎', '誠三郎', '征史郎'];
const intArr = [1, 5, 8, 12, 15, 16];

const rstStr = new Linq(strArr).count(); // => 4
const rstInt = new Linq(intArr).count(x => x % 2 === 0); // => 3

4. where & toArray

const intArr = [0, 1, 2, 3, 4];
// even number
const rst = new Linq(intArr).where(x => x % 2 === 0).toArray(); // => [ 0, 2, 4 ]

5. select & toArray

const parameters = [
  { ID: 5, Rate: 0.0, Name: '正一郎' },
  { ID: 13, Rate: 0.1, Name: '清次郎' },
  { ID: 25, Rate: 0.0, Name: '誠三郎' },
  { ID: 42, Rate: 0.3, Name: '征史郎' }
];

const rst = new Linq(parameters)
  .select(x => {
    return { ID: x.ID, Name: x.Name };
  })
  .toArray();
// =>
// [
//   { ID: 5, Name: "正一郎" },
//   { ID: 13, Name: "清次郎" },
//   { ID: 25, Name: "誠三郎" },
//   { ID: 42, Name: "征史郎" }
// ]

6. selectMany

const parameters = [
  { Name: '正一郎', Numbers: [1, 2, 3] },
  { Name: '清次郎', Numbers: [1, 3, 5] },
  { Name: '誠三郎', Numbers: [2, 4, 6] },
  { Name: '征史郎', Numbers: [9, 8, 7] }
];

const rst = new Linq(parameters).selectMany(x => new Linq(x.Numbers)).toArray(); // => [1, 2, 3, 1, 3, 5, 2, 4, 6, 9, 8, 7]

7. distinct

const intArr = [0, 1, 3, 3, 2];
const parameters = [
  { ID: 5, Rate: 0.0, Name: '正一郎' },
  { ID: 13, Rate: 0.1, Name: '清次郎' },
  { ID: 25, Rate: 0.0, Name: '正一郎' },
  { ID: 42, Rate: 0.3, Name: '征史郎' }
];

const rstInt = new Linq(intArr).distinct().toArray(); // => [ 0, 1, 3, 2 ]
const rstObj = new Linq(parameters)
  .select(x => x.Name)
  .distinct()
  .toArray(); // => [ "正一郎", "清次郎", "征史郎" ]

8. distinctBy

const data = [
  { id: 1, name: 'one', category: 'fruits', countries: ['lxsbw', 'xliecz'] },
  { id: 1, name: 'one', category: 'fruits', countries: ['Italy', 'Austria'] },
  { id: 2, name: 'two', category: 'vegetables', countries: ['Italy', 'Germany'] }
];

const rstKey = new Linq(data).distinctBy(x => x.category).toArray();
const rstKeys = new Linq(data)
  .distinctBy(el => {
    return { id: el.id, category: el.category };
  })
  .toArray();
// rstKey =>
// [
//   { id: 1, name: "one", category: "fruits", countries: [ "lxsbw", "xliecz" ] },
//   { id: 2, name: "two", category: "vegetables", countries: [ "Italy", "Germany" ] }
// ]
// rstKeys =>
// [
//   { id: 1, name: "one", category: "fruits", countries: [ "lxsbw", "xliecz" ] },
//   { id: 2, name: "two", category: "vegetables", countries: [ "Italy", "Germany" ] }
// ]

9. distinctMap

const parameters = [
  { ID: 5, Rate: 0.0, Name: '正一郎' },
  { ID: 13, Rate: 0.1, Name: '清次郎' },
  { ID: 25, Rate: 0.0, Name: '正一郎' },
  { ID: 42, Rate: 0.3, Name: '征史郎' }
];

const rstObj = new Linq(parameters).distinctMap(x => x.Name).toArray(); // => [ "正一郎", "清次郎", "征史郎" ]
const rstObj = new Linq(parameters)
  .distinctMap(x => {
    return { Name: x.Name };
  })
  .toArray(); // => [ { Name: '正一郎' }, { Name: '清次郎' }, { Name: '征史郎' } ]

10. first & firstOrDefault

const numbers = [1, 2, 3, 5, 7, 11];
const parameters = [
  { ID: 5, Name: '正一郎' },
  { ID: 13, Name: '清次郎' },
  { ID: 25, Name: '誠三郎' },
  { ID: 42, Name: '征史郎' }
];

const rstInt = new Linq(numbers).first(); // => 1
const rstObj = new Linq(parameters).firstOrDefault(x => x.ID === 30); // => undefined
const rstObj = new Linq(parameters).firstOrDefault(x => x.ID === 42); // => { ID: 42, Name: '征史郎' }

11. remove

let numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];

console.log(numbers.length); // => 10
new Linq(numbers).remove(6);
console.log(numbers.length); // => 9

12. orderBy & orderByDescending

const parameters = [
  { ID: 0, Name: '正一郎' },
  { ID: 3, Name: '清次郎' },
  { ID: 2, Name: '誠三郎' },
  { ID: 5, Name: '征史郎' }
];

const rst = new Linq(parameters).orderBy(x => x.ID).toArray();
const rstDesc = new Linq(parameters).orderByDescending(x => x.ID).toArray();
// rst =>
// [
//   { ID: 0, Name: "正一郎" },
//   { ID: 2, Name: "誠三郎" },
//   { ID: 3, Name: "清次郎" },
//   { ID: 5, Name: "征史郎" }
// ]
// rstDesc =>
// [
//   { ID: 5, Name: "征史郎" },
//   { ID: 3, Name: "清次郎" },
//   { ID: 2, Name: "誠三郎" },
//   { ID: 0, Name: "正一郎" }
// ]

13. thenBy & thenByDescending

const persons = [
  { ID: 0, Age: 30, Name: 'A' },
  { ID: 1, Age: 25, Name: 'B' },
  { ID: 2, Age: 2, Name: 'G' },
  { ID: 2, Age: 18, Name: 'C' },
  { ID: 1, Age: 30, Name: 'D' },
  { ID: 1, Age: 25, Name: 'E' },
  { ID: 2, Age: 15, Name: 'F' }
];

const rst = new Linq(persons)
  .orderByDescending(x => x.ID)
  .thenBy(x => x.Age)
  .thenByDescending(x => x.Name)
  .toArray();
// 1 orderByDescending =>
// [
//   { ID: 2, Age: 2, Name: "G" },
//   { ID: 2, Age: 18, Name: "C" },
//   { ID: 2, Age: 15, Name: "F" },
//   { ID: 1, Age: 25, Name: "B" },
//   { ID: 1, Age: 30, Name: "D" },
//   { ID: 1, Age: 25, Name: "E" },
//   { ID: 0, Age: 30, Name: "A" }
// ]
// 2 thenBy =>
// [
//   { ID: 2, Age: 2, Name: "G" },
//   { ID: 2, Age: 15, Name: "F" },
//   { ID: 2, Age: 18, Name: "C" },
//   { ID: 1, Age: 25, Name: "B" },
//   { ID: 1, Age: 25, Name: "E" },
//   { ID: 1, Age: 30, Name: "D" },
//   { ID: 0, Age: 30, Name: "A" }
// ]
// 3 thenByDescending =>
// [
//   { ID: 2, Age: 2, Name: "G" },
//   { ID: 2, Age: 15, Name: "F" },
//   { ID: 2, Age: 18, Name: "C" },
//   { ID: 1, Age: 25, Name: "E" },
//   { ID: 1, Age: 25, Name: "B" },
//   { ID: 1, Age: 30, Name: "D" },
//   { ID: 0, Age: 30, Name: "A" }
// ]

14. groupBy

const data = [
  { id: 1, name: 'one', category: 'fruits', countries: ['lxsbw', 'xliecz'] },
  { id: 1, name: 'one', category: 'fruits', countries: ['Italy', 'Austria'] },
  { id: 2, name: 'two', category: 'vegetables', countries: ['Italy', 'Germany'] }
];

const rstKey = new Linq(data).groupBy(el => el.category);
const rstKeys = new Linq(data).groupBy(el => {
  return { id: el.id, category: el.category };
});
// rstKey =>
// [
//   {
//     key: 1, count: 2,
//     elements: [
//       { id: 1, name: "one", category: "fruits", countries: [Array] },
//       { id: 1, name: "one", category: "fruits", countries: [Array] }
//     ]
//   },
//   {
//     key: 2, count: 1,
//     elements: [ { id: 2, name: "two", category: "vegetables", countries: [Array] } ]
//   }
// ]
// rstKeys =>
// [
//   {
//     key: { id: 1, category: "fruits" }, count: 2,
//     elements: [
//       { id: 1, name: "one", category: "fruits", countries: [Array] },
//       { id: 1, name: "one", category: "fruits", countries: [Array] }
//     ]
//   },
//   {
//     key: { id: 2, category: "vegetables" }, count: 1,
//     elements: [ { id: 2, name: "two", category: "vegetables", countries: [Array] } ]
//   }
// ]

15. join

const persons = [
  { CityID: 1, Name: 'ABC' },
  { CityID: 1, Name: 'EFG' },
  { CityID: 2, Name: 'HIJ' },
  { CityID: 3, Name: 'KLM' },
  { CityID: 3, Name: 'NOP' },
  { CityID: 4, Name: 'QRS' },
  { CityID: 5, Name: 'TUV' }
];
const cities = [
  { ID: 1, Name: 'Guangzhou' },
  { ID: 2, Name: 'Shenzhen' },
  { ID: 3, Name: 'Beijing' },
  { ID: 4, Name: 'Shanghai' }
];

const rst = new Linq(persons)
  .join(
    new Linq(cities),
    p => p.CityID,
    c => c.ID,
    (p, c) => {
      return { CityID: c.ID, PersonName: p.Name, CityName: c.Name };
    }
  )
  .toArray();
// rst =>
// [
//   { CityID: 1, PersonName: "ABC", CityName: "Guangzhou" },
//   { CityID: 1, PersonName: "EFG", CityName: "Guangzhou" },
//   { CityID: 2, PersonName: "HIJ", CityName: "Shenzhen" },
//   { CityID: 3, PersonName: "KLM", CityName: "Beijing" },
//   { CityID: 3, PersonName: "NOP", CityName: "Beijing" },
//   { CityID: 4, PersonName: "QRS", CityName: "Shanghai" }
// ]

16. toDictionary

const parameters = [
  { ID: 0, Age: 52, Name: '正一郎' },
  { ID: 8, Age: 28, Name: '清次郎' },
  { ID: 3, Age: 20, Name: '誠三郎' },
  { ID: 4, Age: 18, Name: '征史郎' }
];

const dictionary = new Linq(parameters).toDictionary(x => x.ID).toArray();
const dictionaryObj = new Linq(parameters)
  .toDictionary(x => {
    return { ID: x.ID, Name: x.Name };
  })
  .toArray();
// dictionary =>
// [
//   { Key: 0, Value: { ID: 0, Age: 52, Name: "正一郎" } },
//   { Key: 8, Value: { ID: 8, Age: 28, Name: "清次郎" } },
//   { Key: 3, Value: { ID: 3, Age: 20, Name: "誠三郎" } },
//   { Key: 4, Value: { ID: 4, Age: 18, Name: "征史郎" } }
// ]
// dictionaryObj =>
// [
//   { Key: { ID: 0, Name: "正一郎" }, Value: { ID: 0, Age: 52, Name: "正一郎" } },
//   { Key: { ID: 8, Name: "清次郎" }, Value: { ID: 8, Age: 28, Name: "清次郎" } },
//   { Key: { ID: 3, Name: "誠三郎" }, Value: { ID: 3, Age: 20, Name: "誠三郎" } },
//   { Key: { ID: 4, Name: "征史郎" }, Value: { ID: 4, Age: 18, Name: "征史郎" } }
// ]

17. sum

const parameters = [
  { Age: 52, Name: '正一郎' },
  { Age: 28, Name: '清次郎' },
  { Age: 20, Name: '誠三郎' },
  { Age: 18, Name: '征史郎' }
];

const rst = new Linq(parameters).sum(x => x.Age); // => 118

18. max

const parameters = [
  { Age: 52, Name: '正一郎' },
  { Age: 28, Name: '清次郎' },
  { Age: 20, Name: '誠三郎' },
  { Age: 18, Name: '征史郎' }
];

const rst = new Linq(parameters).max(x => x.Age); // => 52

19. min

const parameters = [
  { Age: 52, Name: '正一郎' },
  { Age: 28, Name: '清次郎' },
  { Age: 20, Name: '誠三郎' },
  { Age: 18, Name: '征史郎' }
];

const rst = new Linq(parameters).min(x => x.Age); // => 18

20. take

const texts = ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'];

const rst = new Linq(texts).take(4).toArray(); // => [ "Sun", "Mon", "Tue", "Wed" ]

21. skip

const texts = ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'];

const rst = new Linq(texts).skip(4).toArray(); // => [ "Thu", "Fri", "Sat" ]

Documentation

If you do not know Linq or just want to remember what is all about, have a look at the docs.

Contributors

Thanks goes to these wonderful people (emoji key):

_{Flavio Corpa} 💻 💬 📖 👀	_{Luis Rogelio Hernández López} 💻 🔧	_{Zsolt Kovács} 💻	_{Mo Abbas} 💻	_{Julián Salgado Napolitano} 💻 🔧	_mstrzoda 💻 🐛 ⚠️	_{Kyle Wascher} ⚠️
_{James Richford} 🔧	_{Natarajan Ganapathi} 💻 🔧	_{Jonas Brekle} 💻 🐛	_LP 💻 ⚠️	_{Asier Ferro} 💻 🔧	_{marlon-tucker} 💻 🔧 📦	_{Misha Sulikashvili} 💻 ⚠️
_{Saurav Sahu} 🚇	_{Bob Cook} 💵	_Adrien 💻	_Lxsbw 💻