Is there a slugify-with-counter helper? How does it work?

Yes, there is a slugifyWithCounter() helper function. Here's how it works:

Overview

slugifyWithCounter() creates a stateful slugify function that automatically appends numeric counters to duplicate slugs. This is useful for generating unique HTML ids for anchors and headlines [index.d.ts:L251-L280].

Behavior

When you call the returned function multiple times with the same or similar input:

• First occurrence: Returns the slug as normal (e.g., 'foo-bar')
• Subsequent identical occurrences: Appends an incrementing counter (e.g., 'foo-bar-2', 'foo-bar-3')

[index.js:L101-L130] shows the implementation:

• It maintains a Map of occurrences to track how many times each slug has been generated
• It extracts the base slug (removing any trailing numbers) to determine if duplicates exist
• If a slug appears 2+ times or the base slug appears more than 2 times total, it appends the counter

Example

import {slugifyWithCounter} from '@sindresorhus/slugify';

const slugify = slugifyWithCounter();

slugify('foo bar');
//=> 'foo-bar'

slugify('foo bar');
//=> 'foo-bar-2'

slugify.reset();

slugify('foo bar');
//=> 'foo-bar'

The reset() method clears the internal counter state, allowing you to start fresh [index.d.ts:L276-L287].

Use Case

This is particularly useful for documents with repeated section titles—for example, if you have multiple "Example" subsections, each will get a unique ID for proper anchor linking.

FOLLOW_UPS:

• What options can be passed to slugifyWithCounter?
• How does the counter detect duplicate base slugs?
• Can you customize the counter format or separator?