Fnjs NPM | npm.io

fn.js

Recreate common functional array methods for objects.

Support

This library currently supports

forEach
some
every
find
findKey
filter
map
mapKeys
reduce
reduceRight

Examples

All following examples return 25.

Plain functions

Using the plain functions.

fn.reduce(
    fn.map(
        fn.filter({
          a: 1,
          b: 2,
          c: 3,
          d: 4,
          e: 5,
          f: 6
        },
        (v) => v % 2 == 0),
    (v) => v * 2),
(sum, v) => v + sum, 1);

Chaining

Using the chain function.

fn.chain({
  a: 1,
  b: 2,
  c: 3,
  d: 4,
  e: 5,
  f: 6
})
.filter(v => v % 2 == 0)
.map(v => v * 2)
.reduce((sum, v) => v + sum, 1)
.value();

Piping

Note: probably easier to use the chaining method, unless you have custom functions you want to use

Using the piping functions.

fn.open({
  a: 1,
  b: 2,
  c: 3,
  d: 4,
  e: 5,
  f: 6
})
.pipe(fn.filter, (v) => v % 2 == 0)
.pipe(fn.map, (v) => v * 2)
.pipe(fn.reduce, (sum, v) => v + sum, 1)
.close();

Casting (not recommended for most scenarios)

Only use this if you're certain you need it.

Casting to a collection object.

fn({
  a: 1,
  b: 2,
  c: 3,
  d: 4,
  e: 5,
  f: 6
})
.filter(v => v % 2 == 0)
.map(v => v * 2)
.reduce((sum, v) => v + sum, 1);

Todo

Avoid calling collect() where possible, to prevent double-iterating
Improve typing for array/object callbacks, to better differentiate return type and callback types
Improve typing for piping
Re-implement acceptance of arrays in collections
Add array describe section to all tests, for completeness