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Generating Random Human-Readable Slugs in JavaScript

Nick Scialli January 13, 2021🚀🚀 6 minute read

Often, we’ll see random, human-readable slugs (e.g., brave-purple-penguin) in the web development world. These slugs offer the uniqueness of a number ID but can be more playful and fun.

How to Generate Random Slugs

The key to generating random slugs is:

  • Identify the parts of speech in each slug position
  • Have a list of words for each part of speech
  • Randomly select from that list as you iterate through the positions.

For example, a common pattern for these slugs is adjective-adjective-noun. You might therefore have a list of adjectives, a list of nouns, and a list of your word order:

const adjective = ['blue', 'smiley', 'funny', 'smelly'];
const noun = ['brick', 'kangeroo', 'penguin', 'laptop'];
const words = { adjective, noun };
const order = ['adjective', 'adjective', 'noun'];

Then, you can map over your order and grab a random element from the corresponding word list:

const selected = order.map(partOfSpeech => {
  const choices = words[partOfSpeech];
  return choices[Math.floor(Math.random() * choices.length)];
});
console.log(selected);
// ['funny', 'blue', 'laptop']

Finally, you will want to join this array with a - character so it’s kebob-cased:

const slug = selected.join('-');
console.log(slug);
// 'funny-blue-laptop'

Using a Package (I Wrote It!)

Of course, this is a pain because you have to come up with the words yourself and it’s not very configurable. Also, you run out of combinations pretty quickly.

To help with this, I made an npm package! It’s called random-word-slugs and it has over 15 million slug combinations (and counting)! Plus, there are a bunch of configuration options, such as being able to specify categories of words that you want.

Read on to see how it works!

Installation

Install with npm

npm i random-word-slugs

Install with yarn

yarn add random-word-slugs

Usage

The random-word-slugs package can be used without any parameters and defaults to a three-word, kebab-cased slug. Currently, the default configuration has 15,660,175 unique slug combinations.

import { generateSlug } from 'random-word-slugs';

const slug = generateSlug();
console.log(slug);
// "elegant-green-coat"

The generateSlug function takes up to two arguments. The first argument is the numberOfWords in the slug (defaulting to three) and the secon argument is the package options. The following example makes use of both parameters and provides an option to title-case the output:

const slug = generateSlug(4, { format: 'title' });
console.log(slug);
// "Elegant Happy Green Coat"

Available Options

The options object can have any partial set of the following key/value pairs:

{
  format: "kebab" | "camel" | "sentence" | "lower" | "title",
  partsOfSpeech: ("adjective" | "noun")[],
  categories: {
    adjective: ("colors" | "appearance" | etc...)[],
    noun: ("person" | "animals" | etc...)[]
  }
}

Note that, if provided, partsOfSpeech must be an array the same length as the number of words you’re requesting. If using Typescript, the compiler will check this for you.

An example of a completed options object might look like this for a three-word slug:

const options = {
  format: 'camel',
  partsOfSpeech: ['adjective', 'noun', 'adjective'],
  categories: {
    adjective: ['colors', 'appearance'],
    noun: ['animals'],
  },
};

Based on these options, our output might look something like blueBearTall.

Typescript Support for Options

The package exposes a RandomWordOptions<N> type, with N being the number of words in the slug. If you want to use this type to specify an options object, it might look something like this (although a Partial options object is certainly allowed and probably more common):

import { RandomWordOptions } from 'random-word-slugs';

const options: RandomWordOptions<3> = {
  format: 'title',
  categories: {
    noun: ['animals', 'places'],
    adjective: ['colors', 'emotions'],
  },
  partsOfSpeech: ['adjective', 'noun', 'adjective'],
};

Importantly, the generic 3 here will enforce partsOfSpeech being a three-element tuple.

Categories

The categories option allows you to generate your random slug from a subset of categories. Perhaps you only want colorful animals! You can specify one or many categories for the adjectives and nouns that comprise your random slug. The following is a list of categories currently in the repository:

Adjective Categories:

  • time
  • appearance
  • color
  • condition
  • personality
  • shapes
  • size
  • sounds
  • taste
  • touch
  • quantity

Noun Categories:

  • people
  • family
  • education
  • religion
  • business
  • animals
  • transportation
  • thing
  • technology
  • place

Assessing the Combinatorics

When using the package, you might be curious about how many different slug combinations exist. The package exposes a function to help with this called totalUniqueSlugs. This function can be used without arguments and will assume a three-slug adjective-adjective-noun format:

import { totalUniqueSlugs } from 'random-word-slugs';

const totalSlugs = totalUniqueSlugs();
console.log(totalSlugs);
// 100000

Note: The 100000 number shown here is just an example and not a representation of the total number of slugs in the package at any moment (that evolves as words are added).

You can also assess the combinatoric space if you have a different number of words, word ordering, or a subset of categories. In the following example, we’ll assume a four-word slug, in the order adjective-noun-adjective-noun, with only color adjectives and animal nouns:

import { totalUniqueSlugs } from 'random-word-slugs';

const totalSlugs = totalUniqueSlugs(4, {
  partsOfSpeech: ['adjective', 'noun', 'adjective', 'noun'],
  categories: {
    adjective: ['colors'],
    noun: ['animals'],
  },
});
console.log(totalSlugs);
// 1000

Again, this 1000 is just an example. Importantly, this could help you determine that you’re not comfortable with this limited combinatoric space and you can choose to add additional categories.

If you'd like to support this blog by buying me a coffee I'd really appreciate it!

Nick Scialli is a software engineer at the U.S. Digital Service.