Merge pull request #29 from PearTree-to/groupBy

Group By util

CHANGELOG

@@ -1,3 +1,6 @@
+#1.13.0
+- feat: groupBy
+
 #1.12.0
 - feat: sum
 - feat: sumBy

README.md

@@ -10,6 +10,7 @@ Currently supported utils:
 - `get` - get the object members by path
 - `getArrayHasIntersect` - checks if arrays have at least one common value
 - `getArrayUniq` - gets unique values form array
+- `groupBy` - groups the elements of an array by a specified key.
 - `isEmpty` - checks if value is an empty object, collection, map, or set
 - `isEqual` - check if passed two values are equal
 - `isFinite` - checks if input is a finite number.

index.d.ts

@@ -6,6 +6,7 @@ export function freezeDeep (obj: Object): Object
 export function get (obj: Object, path: string | Array<string | number>, defaultValue: any): any
 export function getArrayHasIntersect (arr1: Array<any>, arr2: Array<any>): boolean
 export function getArrayUniq (arr: Array<any>): Array<any>
+export function groupBy<T> (array: Array<T>, key: string | ((item: T) => string)): { [key: string]: Array<T> }
 export function isEmpty (val: any): boolean
 export function isEqual (value: any, another: any): boolean
 export function isFinite (val: any): boolean

index.js

@@ -8,6 +8,7 @@ const get = require('./src/get')
 const getArrayHasIntersect = require('./src/getArrayHasIntersect')
 const getArrayUniq = require('./src/getArrayUniq')
 const getErrorMessage = require('./src/getErrorMessage')
+const groupBy = require('./src/groupBy')
 const isEmpty = require('./src/isEmpty')
 const isEqual = require('./src/isEqual')
 const isFinite = require('./src/isFinite')
@@ -38,6 +39,7 @@ module.exports = {
  getArrayHasIntersect,
  getArrayUniq,
  getErrorMessage,
+ groupBy,
  isEmpty,
  isEqual,
  isFinite,

package.json

@@ -1,6 +1,6 @@
 {
  "name": "@bitfinexcom/lib-js-util-base",
- "version": "1.12.0",
+ "version": "1.13.0",
  "description": "general utils",
  "main": "index.js",
  "scripts": {

src/groupBy.js

@@ -0,0 +1,21 @@
+'use strict'
+
+/**
+ * Groups the elements of an array by a specified key.
+ *
+ * @param {Array} array - The array to group.
+ * @param {Function|string} key - The key to group by, or a function to determine the group key.
+ * @returns {Object} An object where keys are group names and values are arrays of grouped items.
+ */
+const groupBy = (array, key) => {
+ return array.reduce((result, item) => {
+ const groupKey = typeof key === 'function' ? key(item) : item[key]
+ if (!result[groupKey]) {
+ result[groupKey] = []
+ }
+ result[groupKey].push(item)
+ return result
+ }, {})
+}
+
+module.exports = groupBy

test/groupBy.js

@@ -0,0 +1,106 @@
+'use strict'
+
+/* eslint-env mocha */
+
+const assert = require('assert')
+const { groupBy } = require('../index')
+
+describe('groupBy', () => {
+ it('should group items by string property key', () => {
+ const items = [
+ { id: 1, category: 'fiat', name: 'USD' },
+ { id: 2, category: 'fiat', name: 'EUR' },
+ { id: 3, category: 'crypto', name: 'USDT' },
+ { id: 4, category: 'fiat', name: 'INR' },
+ { id: 5, category: 'crypto', name: 'EURT' }
+ ]
+
+ const groupedItems = groupBy(items, 'category')
+
+ assert.deepStrictEqual(groupedItems, {
+ fiat: [
+ { id: 1, category: 'fiat', name: 'USD' },
+ { id: 2, category: 'fiat', name: 'EUR' },
+ { id: 4, category: 'fiat', name: 'INR' }
+ ],
+ crypto: [
+ { id: 3, category: 'crypto', name: 'USDT' },
+ { id: 5, category: 'crypto', name: 'EURT' }
+ ]
+ })
+ })
+
+ it('should group items by number property key', () => {
+ const items = [
+ { id: 1, balance: 25 },
+ { id: 2, balance: 30 },
+ { id: 3, balance: 25 },
+ { id: 4, balance: 40 }
+ ]
+
+ const groupedItems = groupBy(items, 'balance')
+
+ assert.deepStrictEqual(groupedItems, {
+ 25: [
+ { id: 1, balance: 25 },
+ { id: 3, balance: 25 }
+ ],
+ 30: [{ id: 2, balance: 30 }],
+ 40: [{ id: 4, balance: 40 }]
+ })
+ })
+
+ it('should group items by computed key using a function', () => {
+ const items = [
+ { id: 1, category: 'fiat', name: 'USD' },
+ { id: 2, category: 'fiat', name: 'EUR' },
+ { id: 3, category: 'crypto', name: 'USDT' },
+ { id: 4, category: 'fiat', name: 'INR' },
+ { id: 5, category: 'crypto', name: 'EURT' }
+ ]
+
+ const groupedItems = groupBy(items, item => item.name.charAt(0))
+
+ assert.deepStrictEqual(groupedItems, {
+ U: [{ id: 1, category: 'fiat', name: 'USD' }, { id: 3, category: 'crypto', name: 'USDT' }],
+ E: [{ id: 2, category: 'fiat', name: 'EUR' }, { id: 5, category: 'crypto', name: 'EURT' }],
+ I: [{ id: 4, category: 'fiat', name: 'INR' }]
+ })
+ })
+
+ it('should group items by function returning a number', () => {
+ const items = [
+ { id: 1, balance: 25 },
+ { id: 2, balance: 30 },
+ { id: 3, balance: 25 },
+ { id: 4, balance: 40 }
+ ]
+
+ const groupedItems = groupBy(items, item => Math.floor(item.balance / 10))
+
+ assert.deepStrictEqual(groupedItems, {
+ 2: [
+ { id: 1, balance: 25 },
+ { id: 3, balance: 25 }
+ ],
+ 3: [{ id: 2, balance: 30 }],
+ 4: [{ id: 4, balance: 40 }]
+ })
+ })
+
+ it('should handle empty array', () => {
+ const items = []
+ const groupedItems = groupBy(items, 'category')
+
+ assert.deepStrictEqual(groupedItems, {})
+ })
+
+ it('should handle array with one item', () => {
+ const items = [{ id: 1, category: 'fiat', name: 'USD' }]
+ const groupedItems = groupBy(items, 'category')
+
+ assert.deepStrictEqual(groupedItems, {
+ fiat: [{ id: 1, category: 'fiat', name: 'USD' }]
+ })
+ })
+})