func-obj

Function over object keys and values into a new object

Install

$ npm install func-obj

Usage

const { map, filter, fold } = require('func-obj');

const newObject = map({foo: 'bar'}, (key, value) => [value, key]);
//=> {bar: 'foo'}

newObject = await map({foo: 'bar'}, (key, value) => Promise.resolve([value, key]), {thenable: true});
//=> {bar: 'foo'}

newObject = filter(object, (key, value) => value === true);
//=> {foo: true}

newObject = await filter(
  {foo: null, bar: {foo: null}},
  (key, value) => new Promise((resolve, reject)=> resolve(value !== null)),
  {deep: true, thenable: true}
);
//=> {foo: true}

newObject = filter({foo: true, bar: false}, ['bar']);
//=> {bar: false}

const obj = { foo: 2, bar: { foo: 1, bar: { foo: 1, bar: 1 } } };
newObject = await fold(obj, (ack, a, b) => ack + b, 1, { deep: true, thenable: true });
// => 5

newObject = await fold(obj, (ack, a, b) => ack + b, 0, { deep: true });
// => 5

API

map(source, mapper, options?)

source

Type: object

Source object to copy properties from.

mapper

Type: Function

Mapping function.

• It has signature mapper(sourceKey, sourceValue, source).
• It must
  • return a two item array: [targetKey, targetValue].
  • or a promise that resolve on two item array: [targetKey, targetValue].

options

Type: object

deep

Type: boolean
Default: false

Recurse nested objects and objects in arrays.

target

Type: object
Default: {}

Target object to map properties on to.

thenable

Type: object
Default: false

Tells if the mapper is handle like a promise or not.

filter(source, filter, options?)

filter(source, includeKeys, options?)

source

Type: object

Source object to filter properties from.

filter

Type: Function

If is a function, predicate function that determines whether a property should be assigned to the new object. The function has the signature filterFunction(sourceKey, sourceValue, source). It must

• return a boolean.
• or a promise that resolve on a boolean.

includeKeys

Type: string[]

Array of property names that should be assigned to the new object.

options

Type: object

deep

Type: boolean
Default: false

Recurse nested objects and objects in arrays.

thenable

Type: object
Default: false

Tells if the mapper is handle like a promise or not.

fold(source, reduce, accumulator, options?)

source

Type: object

Source object to fold properties from.

reduce

Type: Function

• It has signature reducer(accumulator, key, value, source).
• It must
  • return a value that results from the reduction.
  • or a promise that resolve a value that results from the reduction.

accumulator

Type: any

A value to use as the first argument.

options

Type: object

deep

Type: boolean
Default: false

Recurse nested objects and objects in arrays.

thenable

Type: object
Default: false

Tells if the mapper is handle like a promise or not.