Compear ^🍐🤷^🍐

Utilities for comparing and sorting with comparators in JavaScript

Documentation

Installation

npm install compear

What is this?

Let's look at an example. Suppose you have a list of objects...

const people = [
    { firstName: "Tina", lastName: "Ham" },
    { firstName: "Bob", lastName: "Builder" },
    { firstName: "Lewis", lastName: "Mayor" },
];

...and you want to sort the array alphabetically by the "lastName" property.

Without Compear, you can write:

const peopleSorted = people.toSorted((personA, personB) => {
    if (personA.lastName < personB.lastName) {
        return -1;
    } else if (personA.lastName > personB.lastName) {
        return 1;
    } else {
        return 0;
    }
});

With Compear, you can write:

const peopleSorted = people.toSorted(compareBy((person) => person.lastName));

Both examples use the array.toSorted(..) function that is built-in to JavaScript. The difference is in how you write the function that is passed as an argument to array.toSorted(..). This kind of function is called a comparator. Creating and using comparators is what Compear is all about.

Compear is written in TypeScript and provides strong type safety.

Notable features

naturalOrder

naturalOrder is meant to be a sensible default comparator for many cases. It works well for comparing numbers, strings, Dates, or lists of these values. For other types of values, you will probably need to create a more specific comparator.

In some of the provided functions (such as compareBy), Compear uses naturalOrder by default, but allows you to provide a different comparator if needed.

compareBy

The compareBy function can create a comparator that selects a specific property to compare, or somehow derives another value to be compared.

compareWith

compareWith chains together multiple comparators. This is useful when you want to: "sort by X, but if X is equal, then sort by Y, etc."

minWith / maxWith

These functions find the smallest or largest value from a list of values using any given comparator.

See the documentation for more.

Examples

Here are some examples of what you can do with Compear:

import { compareBy, compareByDesc, compareWith, minWith } from "compear";

const heros = [
    {
        name: "Frozone",
        age: 37,
        favoriteColor: "blue",
    },
    {
        name: "Stupendous Man",
        age: 9,
        favoriteColor: "red",
    },
    {
        name: "Iron Man",
        age: 44,
        favoriteColor: "gold",
    },
];

const youngestHero = minWith(heros, compareBy("age"))

const sortedByName = heros.sort(compareBy("name"));

const sortedByNameAndGoldFirst = heros.toSorted(
    compareWith(
        compareByDesc("favoriteColor", (color) => color === "gold"),
        compareBy("name"),
    )
);

About

Compear takes some inspiration from Kotlin's kotlin.comparisons package, but is designed for JavaScript.

Compear embraces functional programming to a certain extent. It prioritizes the treatment of comparator functions as first-class citizens especially because they are highly composable and re-usable in practical applications. On the other hand, some functions have a chosen parameter order that prioritizes readability over the possibility of currying.