Transformers.md

Transformers

Transformers manipulate data in a stream.

They are used as an argument to pipe.

transform

Perform a transformation on the given stream.
Call push to add an item to the stream.

import {from, transform} from 'pure-stream';

from([[1, 2], [3, 4]])
.pipe(transform((numbers, push) => {
  push(numbers[0]);
  push(numbers[1]);
}))
.each(console.log)
.done()

// Output:
// 1
// 2
// 3
// 4

References:
from

map

Apply a function to each item in a stream.

import {from, map} from 'pure-stream';

from([1, 2, 3])
.pipe(map((value) => value * 2))
.each(console.log)
.done()

// Output:
// 2
// 4
// 6

References:
from

reduce

Reduce the items in a stream using the given function.

import {from, reduce} from 'pure-stream';

from([1, 2, 3])
.pipe(reduce((prev, next) => prev + next, 0))
.each(console.log)
.done()

// Output:
// 6

References:
from

filter

Filter out items in a stream using the given function.

import {from, reduce} from 'pure-stream';

from([1, 2, 3])
.pipe(filter((value) => value % 2 === 1))
.each(console.log)
.done()

// Output:
// 1
// 3

References:
from

chunk

Combine the items in a stream into chunks of the given size.

import {from, chunk} from 'pure-stream';

from([1, 2, 3])
.pipe(chunk(2))
.each(console.log)
.done()

// Output:
// [1, 2]
// [3]

References:
from

chunkMap

Combine the items in a stream into chunks of the given size and apply a function to each chunk.

import {from, chunkMap} from 'pure-stream';

from([1, 2, 3])
.pipe(chunkMap(2, (chunk) => chunk.length))
.each(console.log)
.done()

// Output:
// 2
// 1

References:
from