How to slugify a string in JavaScript

A slug is a string that is used to uniquely identify a resource in a URL-friendly way. It is typically used in the URL to identify a specific page or post on a website. A slug consists of a set of characters that are easy to read and remember, and that accurately describe the content of the resource.

A string can be qualified as a slug if it meets the following criteria:

• It consists of lowercase alphanumeric characters (a-z,0-9) and hyphens (-).
• It does not contain any spaces or other special characters.
• It accurately and concisely describes the content of the resource it identifies.
• It is unique within the context of the website or application.

For example, consider the following URL https://byby.dev/react-data-fetching-libraries. In this URL, react-data-fetching-libraries is the slug that identifies the specific blog post.

A simple slugify

In JavaScript, you can slugify a string by converting it to a URL-friendly format where any special characters and spaces are replaced with hyphens or underscores. Here's an example function that can accomplish this:

function slugify(str) {  str = str.replace(/^\s+|\s+$/g, ''); // trim leading/trailing white space  str = str.toLowerCase(); // convert string to lowercase  str = str.replace(/[^a-z0-9 -]/g, '') // remove any non-alphanumeric characters           .replace(/\s+/g, '-') // replace spaces with hyphens           .replace(/-+/g, '-'); // remove consecutive hyphens  return str;}const title = "The Quick Brown Fox Jumps Over The Lazy Dog!";const slug = slugify(title);console.log(slug); // "the-quick-brown-fox-jumps-over-the-lazy-dog"

Using a library

There are several libraries available in JavaScript that can be used to slugify a string easily without having to write custom code.

• lodash (56k ) This library provides a wide range of utility functions for JavaScript, including a kebabCase function that can be used to convert a string to kebab case, which is similar to slug format. Kebab case format is a naming convention where words are separated by a hyphen (-) and all letters are in lower case.

const _ = require('lodash');const myString = 'Hello World';const kebabCaseString = _.kebabCase(myString);console.log(kebabCaseString); // Output: hello-world

• Voca (3.5k ) The Voca library offers helpful functions to make string manipulations comfortable: change case, trim, pad, slugify, latinise, sprintf'y, truncate, escape and much more. In Voca, slugify is a function that converts a string to a URL-friendly slug format.

const { slugify } = require('voca');const myString = 'Hello World!';const slugifiedString = slugify(myString);console.log(slugifiedString); // Output: hello-world

• @sindresorhus/slugify (2.3k ) Useful for URLs, filenames, and IDs. It handles most major languages, including German (umlauts), Vietnamese, Arabic, Russian, and more.

const slugify = require('@sindresorhus/slugify');slugify('I  Dogs'); // i-love-dogsslugify('  Dj Vu!  '); // deja-vuslugify('fooBar 123 $#%'); // foo-bar-123slugify('  '); // ya-lyublyu-edinorogovslugify('BAR and baz', {separator: '_'}); // bar_and_bazslugify('BAR and baz', {separator: ''}); // barandbaz

• slugify (1.2k ) This library includes a simple slugify function in vanilla ES2015 JavaScript, has no dependencies, coerces foreign symbols to their English equivalent, works in the browser (window.slugify) and AMD/CommonJS-flavored module loaders.

const slugify = require('slugify');slugify('some string'); // some-string// if you prefer something other than '-' as separatorslugify('some string', '_');  // some_string

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