map-obj

What is map-obj?

The map-obj package is a utility that allows you to map object keys and values into a new object. It provides a simple way to transform objects based on a mapping function.

What are map-obj's main functionalities?

Mapping keys and values

You can map the keys and values of an object to new keys and values. For example, you can take an object with keys 'foo' and 'bar' and transform them into 'newFoo' and 'newBar' with corresponding values.

{"newKey": "newValue"}

Custom mapping function

The package allows you to provide a custom mapping function that receives the key and value of each property and returns a new key-value pair array. This function is applied to each property in the original object.

const mapObj = require('map-obj');
const newObject = mapObj({ foo: 'bar' }, (key, value) => [key.toUpperCase(), value.repeat(3)]);

Deep mapping

map-obj supports deep mapping, which means you can apply the mapping function recursively to nested objects.

const mapObj = require('map-obj');
const newObject = mapObj({ foo: { bar: 'baz' } }, (key, value) => [key, value], { deep: true });

Target option

You can specify a target object to which the mapped properties will be assigned. This allows you to merge the new properties with an existing object.

const mapObj = require('map-obj');
const target = { existing: 'prop' };
const newObject = mapObj({ foo: 'bar' }, (key, value) => [key, value], { target });

Other packages similar to map-obj

lodash.mapkeys

lodash.mapkeys is a method from the Lodash library that allows you to create an object with the same values as the original object but with keys mapped using a provided function. It is similar to map-obj but is part of the larger Lodash utility library.

object-map

object-map is a package that provides a function to map the values of an object to new values based on a provided function. It is similar to map-obj but focuses only on mapping values, not keys.

deep-map-object

deep-map-object is a package that allows deep mapping of object keys and values. It is similar to map-obj's deep mapping feature but is specifically designed for deep transformations.

README

map-obj

Map object keys and values into a new object

Install

npm install map-obj

Usage

import mapObject, {mapObjectSkip} from 'map-obj';

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

const newObject = mapObject({FOO: true, bAr: {bAz: true}}, (key, value) => [key.toLowerCase(), value]);
//=> {foo: true, bar: {bAz: true}}

const newObject = mapObject({FOO: true, bAr: {bAz: true}}, (key, value) => [key.toLowerCase(), value], {deep: true});
//=> {foo: true, bar: {baz: true}}

const newObject = mapObject({one: 1, two: 2}, (key, value) => value === 1 ? [key, value] : mapObjectSkip);
//=> {one: 1}

API

mapObject(source, mapper, options?)

source

Type: object

The source object to copy properties from.

mapper

Type: (sourceKey, sourceValue, source) => [targetKey, targetValue, mapperOptions?] | mapObjectSkip

A mapping function.

mapperOptions

Type: object

shouldRecurse

Type: boolean
Default: true

Whether targetValue should be recursed.

Requires deep: true.

options

Type: object

deep

Type: boolean
Default: false

Recurse nested objects and objects in arrays.

target

Type: object
Default: {}

The target object to map properties on to.

mapObjectSkip

Return this value from a mapper function to exclude the key from the new object.

import mapObject, {mapObjectSkip} from 'map-obj';

const object = {one: 1, two: 2}
const mapper = (key, value) => value === 1 ? [key, value] : mapObjectSkip
const result = mapObject(object, mapper);

console.log(result);
//=> {one: 1}

Related

• filter-obj - Filter object keys and values into a new object

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