ObjecTools

Useful easy-to-use utilities for JavaScript objects

Table of contents

• Features
• Installation
• Usage
• Examples
  • .filter()
  • .map(), .mapKeyValue
  • .keys, .values, .entries, .length
  • .find(), .findIndex(), .findKey(), .findValue()
  • .findLast(), .findLastIndex(), .findLastKey(), .findLastValue()
  • .indexOf(), .lastIndexOf(), .indexOfKey()
  • .sort(), .sortByValues()
  • .some(), .every()
  • .omit()
  • .flip()
  • .reverse()
  • Chain methods
  • .transpose()
• Usage with Jest

Features

• Easy to use, w/o modifying object prototype (o(obj).filter(...))
• Useful methods that are operable on keys, values and indices (see Examples):
  • filter()
  • map() & mapKeyValue(), forEach()
  • find(), findIndex(), findLast(), findLastIndex()
  • indexOf(), lastIndexOf(), indexOfKey()
  • sort(),
  • reverse()
  • some(), every()
  • omit() // omit key(s)
  • flip(), transpose()
• and properties:
  • .length
  • .keys, .values, .entries
• Provides an easy way to chain methods
• Typed keys and values
• No dependency, based on modern JS features
• Memory and processor efficient
• Returns Set instead of Array for .keys ( see: Why does Object.keys() return an Array instead of a Set?)

Installation

npm i objectools

or:

yarn add objectools

Usage

import o from 'objectools'

o({a: 1, b: 2, c: 3}).filter(/*...*/)
o({a: 1, b: 2, c: 3}).map(/*...*/)
o({a: 1, c: 3, b: 2}).sort()
o({...}) //...

// Or chain methods:
o({...}).oFilter(/*...*/).oMap(/*...*/).sort() // Don't prefix the last one with `o`.
// I.e. don't write `.oSort()` if you don't want to countinue the chain.

Examples

.filter()

o({a: 1, b: 2, c: 3}).filter((value) => value > 1) // {b: 2, c: 3}
o({a: 1, b: 2, c: 3}).filter((_, key, index) => key < 'c' && index > 0) // {b: 2}

.map()

o({a: 1, b: 2, c: 3}).map((value) => value * 2) // {a: 2, b: 4, c: 6}
o({a: 1, b: 2, c: 3}).mapKeyValue((value, key) => [key.toUpperCase(), value - 1]) // {A: 0, B: 1, C: 2}

.keys, .values, .entries, .length

o({a: 1, b: 2, c: 3}).keys // Set {'a', 'b', 'c'} // Type: `Set<'a' | 'b' | 'c'>`
o({a: 1, b: 2, c: 3}).values // [1, 2, 3] // Type: `number[]`
o({a: 1, b: 2, c: 3}).entries // [['a', 1], ['b', 2], ['c', 3]] // Type: ['a' | 'b' | 'c', number][]
o({a: 1, b: 2, c: 3}).length // 3

.find(), .findIndex(), .findKey(), .findValue()

o({a: 1, b: 2, c: 3}).find((value) => value > 1) // ['b', 2]
o({a: 1, b: 2, c: 3}).findIndex((value) => value > 1) // 1
o({a: 1, b: 2, c: 3}).findKey((value) => value > 1) // 'b'
o({a: 1, b: 2, c: 3}).findValue((value) => value > 1) // 2

.findLast(), .findLastIndex(), .findLastKey(), .findLastValue()

o({a: 1, b: 2, c: 3}).findLast((value) => value > 1) // ['c', 3]
o({a: 1, b: 2, c: 3}).findLastIndex((value) => value > 1) // 2
o({a: 1, b: 2, c: 3}).findLastKey((value) => value > 1) // 'c'
o({a: 1, b: 2, c: 3}).findLastValue((value) => value > 1) // 3

.indexOf(), .lastIndexOf(), .indexOfKey()

o({a: 3, b: 3}).indexOf(3) // 0
o({a: 3, b: 3}).lastIndexOf(3) // 1
o({a: 3, b: 3}).indexOfKey('b') // 1

.sort(), .sortByValues()

o({b: 1, a: 3, c: 2}).sort() // {a: 3, b: 1, c: 2}
o({b: 1, a: 3, c: 2}).sortByValues() // {b: 1, c: 2, a: 3}

.some(), .every()

o({a: 1, b: 2, c: 3}).some((value) => value > 1) // true
o({a: 1, b: 2, c: 3}).every((value) => value > 1) // false

.omit()

o({a: 1, b: 2, c: 3}).omit('b') // {a: 1, c: 3}
o({a: 1, b: 2, c: 3}).omit('c', 'a') // {b: 2}

.flip()

o({a: 'x', b: 'y'}).flip() // {x: 'a', y: 'b'}

.reverse()

o({a: 'x', b: 'y'}).reverse() // {b: 'y', a: 'x'}

Chain methods

o({b: 1, a: 2, c: 3})
  .oFilter((value) => value < 3)
  .oMap((value) => value * 2)
  .sort()
// --> {a: 4, b: 2}

.transpose()

o({
  x: {a: 1, b: 2},
  y: {a: 3, b: 4},
  z: {a: 5, b: 6},
}).transpose()
// -->
// {
//   a: {x: 1, y: 3, z: 5},
//   b: {x: 2, y: 4, z: 6},
// }

Usage with Jest

You may need to add this to your "jest.config.js" file:

export default {
  transformIgnorePatterns: [
    // These packages are created based on modern javascript and use ESM module system (import/export). But Jest use
    // old common-js module-system. So we need to transform these files using babel, too (like source files). Note that
    // "node_modules" folder is ignored by default, and we've EXCLUDED these packages from this general rule (see `?!`
    // in the below regex).
    '/node_modules/(?!(objectools)/)',
}

See: https://stackoverflow.com/a/49676319/5318303/#jest-gives-an-error-syntaxerror-unexpected-token-export