slugify.ts

// string.js slugify drops non ascii chars so we have to
// use a custom implementation here

// eslint-disable-next-line no-control-regex
const rControl = /[\u0000-\u001f]/g
const rSpecial = /[\s~`!@#$%^&*()\-_+=[\]{}|\\;:"'“”‘’–—<>,.?/]+/g
const rCombining = /[\u0300-\u036F]/g

export = function slugify (str: string): string {
  // Split accented characters into components
  return str.normalize('NFKD')
    // Remove links, just leave hyperlink's text
    .replace(/^\[(.*)?(]\(.*?\))$/g,'$1')
    // Remove accents
    .replace(rCombining, '')
    // Remove control characters
    .replace(rControl, '')
    // Replace special characters
    .replace(rSpecial, '-')
    // Remove continuous separators
    .replace(/\-{2,}/g, '-')
    // Remove prefixing and trailing separators
    .replace(/^\-+|\-+$/g, '')
    // ensure it doesn't start with a number (#121)
    .replace(/^(\d)/, '_$1')
    // lowercase
    .toLowerCase()
}