slug.js

const slug = s => s
  .toString()                       // ensure string
  .normalize("NFD")                 // convert to unicode normalization form using (N)normalization (F)form canonical (D)decomposition
                                    // aka. remove accent and leave base
  .replace(/[\u0300-\u036f]/g, "")  // remove range combining grave accent to combining lating small letter x
  .toLowerCase()                    // lower chars
  .trim()                           // trim whitespace
  .replace(/\s+/g, '-')             // replace space(s) with dash
  .replace(/[^\w-]+/g, "")          // remove things not a-z A-Z 0-9 or -
  .replace(/--+/g, '-')             // replace double dash with single dash

// 90% SO copy/paste