# String Natural Compare [![NPM Version](https://img.shields.io/npm/v/string-natural-compare.svg)](https://www.npmjs.com/package/string-natural-compare) [![Build Status](https://travis-ci.org/nwoltman/string-natural-compare.svg?branch=master)](https://travis-ci.org/nwoltman/string-natural-compare) [![Coverage Status](https://coveralls.io/repos/nwoltman/string-natural-compare/badge.svg?branch=master)](https://coveralls.io/r/nwoltman/string-natural-compare?branch=master) [![Dependencies Status](https://img.shields.io/david/nwoltman/string-natural-compare)](https://david-dm.org/nwoltman/string-natural-compare) Compare alphanumeric strings the same way a human would, using a natural order algorithm (originally known as the [alphanum algorithm](http://davekoelle.com/alphanum.html)) where numeric characters are sorted based on their numeric values rather than their ASCII values. ``` Standard sorting: Natural order sorting: img1.png img1.png img10.png img2.png img12.png img10.png img2.png img12.png ``` This module exports a function that returns a number indicating whether one string should come before, after, or is the same as another string. It can be used directly with the native [`.sort()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort) array method. ### Fast and Robust This module can compare strings containing any size of number and is heavily tested with a custom [benchmark suite](https://github.com/nwoltman/string-natural-compare/tree/master/benchmark) to make sure that it is as fast as possible. ## Installation ```sh npm install string-natural-compare --save # or yarn add string-natural-compare ``` ## Usage #### `naturalCompare(strA, strB[, options])` + `strA` (_string_) + `strB` (_string_) + `options` (_object_) - Optional options object with the following options: + `caseInsensitive` (_boolean_) - Set to `true` to compare strings case-insensitively. Default: `false`. + `alphabet` (_string_) - A string of characters that define a custom character ordering. Default: `undefined`. ```js const naturalCompare = require('string-natural-compare'); // Simple, case-sensitive sorting const files = ['z1.doc', 'z10.doc', 'z17.doc', 'z2.doc', 'z23.doc', 'z3.doc']; files.sort(naturalCompare); // -> ['z1.doc', 'z2.doc', 'z3.doc', 'z10.doc', 'z17.doc', 'z23.doc'] // Case-insensitive sorting const chars = ['B', 'C', 'a', 'd']; const naturalCompareCI = (a, b) => naturalCompare(a, b, {caseInsensitive: true}); chars.sort(naturalCompareCI); // -> ['a', 'B', 'C', 'd'] // Note: ['a', 'A'].sort(naturalCompareCI); // -> ['a', 'A'] ['A', 'a'].sort(naturalCompareCI); // -> ['A', 'a'] // Compare strings containing large numbers naturalCompare( '1165874568735487968325787328996865', '265812277985321589735871687040841' ); // -> 1 // (Other inputs with the same ordering as this example may yield a different number > 0) // Sorting an array of objects const hotelRooms = [ {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) hotelRooms.sort((a, b) => ( naturalCompare(a.street, b.street, {caseInsensitive: true}) || naturalCompare(a.room, b.room) )); // When text transformation is needed or when doing a case-insensitive sort on a // large array of objects, it is best for performance to pre-compute the // transformed text and store it on the object. This way, the text will not need // to be transformed for every comparison while sorting. const cars = [ {make: 'Audi', model: 'R8'}, {make: 'Porsche', model: '911 Turbo S'} ]; // Sort by make, then by model (both case-insensitive) for (const car of cars) { car.sortKey = (car.make + ' ' + car.model).toLowerCase(); } cars.sort((a, b) => naturalCompare(a.sortKey, b.sortKey)); // Using a custom alphabet (Russian alphabet) const russianOpts = { alphabet: 'АБВГДЕЁЖЗИЙКЛМНОПРСТУФХЦЧШЩЪЫЬЭЮЯабвгдеёжзийклмнопрстуфхцчшщъыьэюя', }; ['Ё', 'А', 'б', 'Б'].sort((a, b) => naturalCompare(a, b, russianOpts)); // -> ['А', 'Б', 'Ё', 'б'] ``` **Note:** Putting numbers in the custom alphabet can cause undefined behaviour.