@aeinbu/groupby

Lightweight and non-intrusive functions for doing "group by" and "distinct" (aka. "unique") transformations on collections using reducers

• The functions are lightweight, as they are small and don't make you bring along lots of functions you don't need.
• The functions are flexible since you can choose how to best represent your grouped data
  • An array of key-value pairs that are easy to further process using .map(...), .filter(...) and other built-in array functions
  • A dictionary in the shape of a standard javascript object or an ES2015 built-in Map
• These functions run just as well in a browser as they do in nodejs.
• The package is non-intrusive, as it doesn't extend arrays adding new and non-standard methods to them.
  • This is done by having functions that you use with .reduce(...) on arrays.
• @types are included for better discoverability during development when you use editors with javascript/typescript intellisence support

How to install

With npm

npm install @aeinbu/groupby

...or with yarn

yarn add @aeinbu/groupby

Quickstart

import { groupBy, toMap } from "@aeinbu/groupby"

const people = [
    {name: "Tony", residence: "Rome"},
    {name: "Mary", residence: "Rome"},
    {name: "Peter", residence: "London"},
    {name: "Peter", residence: "Rome"},
    {name: "Elisabeth", residence: "London"},
    {name: "Francois", residence: "Paris"}
]

const results = people
    .reduce(groupBy(x => x.name, x => x.residence), [])
    .reduce(toMap(x => x.name), new Map())

// With the same results as above:
// {
//     "Rome": ["Tony", "Mary", "Peter"],
//     "London": ["Peter", "Elisabeth"],
//     "Paris": ["Francois"]
// }

Documentation

For more documentation, follow these links:

• groupBy
• distinctBy and distinct
• toMap
• toDictionary
• isDeepEqual

Also, look in the tests directory for more examples. The tests demonstrate at least another dozen different ways to use this library

Semantic versioning

This package follows semantic versioning (See semver.org for more info)

License

This package is published under the MIT License. (See LICENSE file for more info)