mattbalmer/fnjs

Functional methods that handle Maps and Arrays alike.

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

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

Contact & License Info

Author: Matthew Balmer
Email: [email protected]
Twitter: @mattbalmer
Website: http://mattbalmer.com
License: MIT