string-natural-compare

What is string-natural-compare?

The string-natural-compare npm package provides a way to compare strings in a human-friendly manner, often referred to as 'natural order' comparison. This is particularly useful for sorting lists of strings that include numbers, where you want the numbers to be sorted in numerical order rather than lexicographical order.

What are string-natural-compare's main functionalities?

Basic Natural Comparison

This feature allows you to compare two strings in a natural order. In this example, 'file10' is compared to 'file2', and the result is 1, indicating that 'file10' comes after 'file2' in natural order.

const naturalCompare = require('string-natural-compare');

const result = naturalCompare('file10', 'file2');
console.log(result); // Output: 1

Sorting an Array

This feature allows you to sort an array of strings in natural order. In this example, the array ['file10', 'file2', 'file1'] is sorted to ['file1', 'file2', 'file10'].

const naturalCompare = require('string-natural-compare');

const files = ['file10', 'file2', 'file1'];
files.sort(naturalCompare);
console.log(files); // Output: ['file1', 'file2', 'file10']

Case-Insensitive Comparison

This feature allows you to perform a case-insensitive natural comparison. In this example, 'File10' is compared to 'file2' with case insensitivity, and the result is 1, indicating that 'File10' comes after 'file2' in natural order.

const naturalCompare = require('string-natural-compare');

const result = naturalCompare('File10', 'file2', { caseInsensitive: true });
console.log(result); // Output: 1

Other packages similar to string-natural-compare

natural-compare-lite

The natural-compare-lite package provides similar functionality for natural order string comparison but is designed to be a lighter and faster alternative. It lacks some of the additional options available in string-natural-compare, such as case insensitivity.

alphanum-sort

The alphanum-sort package offers alphanumeric sorting of arrays, which is similar to natural order comparison. It is optimized for performance and can handle large arrays efficiently. However, it does not provide as many customization options as string-natural-compare.

README

String Natural Compare

Compare alphanumeric strings the same way a human would, using a natural order algorithm

---

Important: The API has changed between v1 and v2. If upgrading, check out the migration guide. If using the Bower module (or v1 npm module), see the v1 API.

---

Standard sorting:   Natural order sorting:
    img1.png            img1.png
    img10.png           img2.png
    img12.png           img10.png
    img2.png            img12.png

This module provides two functions:

• naturalCompare
• naturalCompare.caseInsensitive (alias: naturalCompare.i)

These functions return a number indicating whether one string should come before, after, or is the same as another string. They can be easily used with the native .sort() array method.

Fast and Robust

This module uses a performant and robust algorithm to compare alphanumeric strings. It can compare strings containing any size of number and is heavily tested with a custom benchmark suite to make sure that it is as fast as possible, even when a custom alphabet has been configured.

Installation

npm:

npm install string-natural-compare --save

Bower (only up to v1.1.1):

bower install string-natural-compare

Include the script in your HTML (drop the ".min" to use the development version):

<script src="/bower_components/string-natural-compare/natural-compare.min.js"></script>

Note: IE8 and lower not supported.

Usage

var naturalCompare = require('string-natural-compare');

// Simple case-sensitive sorting
var a = ['z1.doc', 'z10.doc', 'z17.doc', 'z2.doc', 'z23.doc', 'z3.doc'];
a.sort(naturalCompare);
// -> ['z1.doc', 'z2.doc', 'z3.doc', 'z10.doc', 'z17.doc', 'z23.doc']


// Simple case-insensitive sorting
var a = ['B', 'C', 'a', 'd'];
a.sort(naturalCompare.caseInsensitive); // alias: a.sort(naturalCompare.i);
// -> ['a', 'B', 'C', 'd']

// Note:
['a', 'A'].sort(naturalCompare.caseInsensitive); // -> ['a', 'A']
['A', 'a'].sort(naturalCompare.caseInsensitive); // -> ['A', 'a']


// Compare strings containing large numbers
naturalCompare(
  '1165874568735487968325787328996865',
  '265812277985321589735871687040841'
);
// -> 1 (a number > 0)


// In most cases we want to sort an array of objects
var a = [
  {street: '350 5th Ave', room: 'A-1021'},
  {street: '350 5th Ave', room: 'A-21046-b'}
];

// Sort by street (case-insensitive), then by room (case-sensitive)
a.sort(function(a, b) {
  return (
    naturalCompare.caseInsensitive(a.street, b.street) ||
    naturalCompare(a.room, b.room)
  );
});


// When text transformation is needed or when doing a case-insensitive sort on a
// large array, it is best for performance to pre-compute the transformed text
// and store it in that object. This way, the text transformation will not be
// needed for every comparison when sorting.
var a = [
  {make: 'Audi', model: 'R8'},
  {make: 'Porsche', model: '911 Turbo S'}
];

// Sort by make, then by model (both case-insensitive)
a.forEach(function(car) {
  car.sortKey = (car.make + ' ' + car.model).toLowerCase();
});
a.sort(function(a, b) {
  return naturalCompare(a.sortKey, b.sortKey);
});

Custom Alphabet

It is possible to configure a custom alphabet to achieve a desired character ordering.

// Estonian alphabet
naturalCompare.alphabet = 'ABDEFGHIJKLMNOPRSŠZŽTUVÕÄÖÜXYabdefghijklmnoprsšzžtuvõäöüxy';
['t', 'z', 'x', 'õ'].sort(naturalCompare);
// -> ['z', 't', 'õ', 'x']

// Russian alphabet
naturalCompare.alphabet = 'АБВГДЕЁЖЗИЙКЛМНОПРСТУФХЦЧШЩЪЫЬЭЮЯабвгдеёжзийклмнопрстуфхцчшщъыьэюя';
['Ё', 'А', 'б', 'Б'].sort(naturalCompare);
// -> ['А', 'Б', 'Ё', 'б']

Note: Putting numbers in the custom alphabet can cause undefined behaviour.

Migration Guide

Upgrading from v1 to v2

The module must now be required like so:

var naturalCompare = require('string-natural-compare');

Then the following replacements need to be made:

• String.naturalCompare → naturalCompare
• String.naturalCaseCompare → naturalCompare.caseInsensitive (or the alias naturalCompare.i)
• String.alphabet → naturalCompare.alphabet