fxjs2

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FxJS - Functional Extensions for Javascript

FxJS is a functional programming library that uses basic JavaScript values ​​and emphasizes repeatable programming and Promise.

iterable

const res = go(
  L.range(Infinity),
  L.filter(a => a % 2),
  L.take(3),
  reduce(add));

log(res); // 9

iterable + time

go(
  L.range(Infinity),
  L.map(delay(1000)),
  L.map(a => a + 10),
  L.take(3),
  each(log));
// After 1 second 10
// After 2 seconds 11
// After 3 seconds 12

iterable + time + Promise

// L.interval = time => L.map(delay(time), L.range(Infinity));

(async () => {
  await go(
    L.interval(1000),
    L.map(a => a + 30),
    L.takeUntil(a => a == 33),
    each(log));
  // After 1 second 30
  // After 2 seconds 31
  // After 3 seconds 32
  // After 4 seconds 33

  const res = await go(
    L.interval(1000),
    L.map(a => a + 20),
    L.takeWhile(a => a < 23),
    L.map(tap(log)),
    reduce(add));
  // After 5 seconds 20
  // After 6 seconds 21
  // After 7 seconds 22

  log(res);
  // 63
} ());

Install

npm i fxjs2

API

• map
• filter
• reduce
• take
• L.map
• L.filter
• go + try catch + Asynchronous error handling
• stop

map

map(a => a + 10, [1, 2, 3]);
// [11, 12, 13]

filter

filter(a => a % 2, [1, 2, 3]);
// [1, 3]

reduce

const add = (a, b) => a + b
reduce(add, [1, 2, 3]);
// 6

reduce(add, 10, [1, 2, 3]);
// 16

reduce(add, {a: 1, b: 2, c: 3});
// 6

await reduce(add, [Promise.resolve(1), 2, 3])
// 6

take

take(1, [1, 2, 3]);
// [1]

take(2, [1, 2, 3])
// [1, 2]

L.map

const iterator = L.map(a => a + 10, [1, 2, 3]);
take(2, iterator);
// [11, 12]

L.filter

const iterator = L.filter(a => a % 2, [1, 2, 3, 4, 5]);
take(2, iterator);
// [1, 3]

const iterator = L.filter(a => a % 2, L.map(a => a + 10, [1, 2, 3, 4, 5]));
take(2, iterator);
// [11, 13]

go + try catch + Asynchronous error handling

const b = go(
  0,
  a => a + 1,
  a => a + 10,
  a => a + 100);

console.log(b);
// 111

try {
  const b = go(
    0,
    a => { throw { hi: 'ho' } },
    a => a + 10,
    a => a + 100);

  console.log(b);
} catch (c) {
  console.log(c);
}
// { hi: 'ho' }

const b = await go(
  0,
  a => Promise.resolve(a + 1),
  a => a + 10,
  a => a + 100);

console.log(b);
// 111

try {
  const b = await go(
    0,
    a => Promise.resolve(a + 1),
    a => Promise.reject({ hi: 'ho' }),
    a => a + 100);

  console.log(b);
} catch (c) {
  console.log(c);
}
// { hi: 'ho' }

try {
  const b = await go(
    0,
    a => Promise.resolve(a + 1),
    a => Promise.reject({ hi: 'ho' }),
    a => a + 100);

  console.log(b);
} catch (c) {
  console.log(c);
}
// { hi: 'ho' }

stop

const f1 = pipeS(
  a => a % 2 ? stop(a) : a,
  a => a + 10);
f1(1); // 1
f1(2); // 12

goS({a: 1, b: 2},
  stopIf({a: 1}),
  ({a, b}) => ({a: a + 10, b})); // {a: 1, b: 2}

goS({a: 2, b: 2},
  stopIf({a: 1}),
  ({a, b}) => ({a: a + 10, b})); // {a: 12, b: 2}

goS({a: 1, b: 2},
  stopIf({a: 1}, null),
  ({a, b}) => ({a: a + 10, b}));
// null