reduce-to

convert and modify Arrays, Objects, Maps, Sets and Strings. A powerful utility belt well under 1kb gzip, no dependencies

example

var x = require('reduce-to')

// CONVERSIONS
var source = ['a', 'b', 'c'],
    map = x(source, new Map), // Map of [0,'a'], [1, 'b'], [2, 'c']
    obj = x(map, {}), // {'0': 'a', '1': 'b', '2': 'c'}
    set = x(obj, new Set) // Set of 'a', 'b', 'c'
    txt = x(set, '') // 'abc'
    arr = x(txt, []) // same as source

// LAZY TRANSFORMS WITH TRANSDUCERS
var zAC = x(
  set, //start from any of the supported types
  x.filter(v=>v!=='b'), //filter transducer
  x.map(v=>v.toUpperCase(), //map transducer
  'z' //target with initial value
)) // 'zAC

Features

• apply multiple transforms in a lazy and efficient way
• convert to any javascript key-value data types
  • var myMap = x(JSON.parse(json), new Map)
  • var json = x(set, [])
  • var noDuplicates = x(x(arr, new Set), [])
  • var shallowClone = x(obj, {})
  • var plusOne = x(new Int8Array([1,2,3]), x.map(v=>v+1)) converted to an Array
• works seamlesly in ES5

supported types

• Input: Array, Strings, Object, Map, Set, Iterators
• Output: Array, Strings, Object, Map, Set, WeakMap, WeakSet

key value conversions

• Array: index, value
• String: index, value
• Object: key, value
• Map: key.toString(), value
• Set: index, value
• Iterators: index, value

transducer and reducer functions

To keep things light and simple, only 3 reducer types are provided

• .map((val, key, source) => newValue)
• .filter((val, key, source) => Boolean)
• .index((val, index, source) => Boolean)

index is similar to filter but with a counter index instead of the key (same as Array.filter). Most common other reducers can be emulated with these 3 base reducers:

• take(N): use index((val, idx) => idx < N)
• drop(N): use index((val, idx) => idx >= N)
• ...reject, dropWhile, ...

License

MIT © Hugo Villeneuve