superflected/src/parameterize.ts

A port of ActiveSupport's inflector to Node.js

import { cacheable } from "./cacheable";
import { transliterate } from "./Transliterator";

export const parameterize = cacheable(
  (string: string, options: { locale?: string; separator?: string | null; preserveCase?: boolean } = {}) => {
    if (options.separator === undefined) {
      options.separator = "-";
    }

    if (options.separator === null) {
      options.separator = "";
    }

    // replace accented chars with their ascii equivalents
    let result = transliterate(string, { locale: options.locale });

    result = result.replace(/[^a-z0-9\-_]+/gi, options.separator);

    if (options.separator.length) {
      const separatorRegex = new RegExp(options.separator);

      // no more than one of the separator in a row
      result = result.replace(new RegExp(separatorRegex.source + "{2,}"), options.separator);

      // remove leading/trailing separator
      result = result.replace(new RegExp("^" + separatorRegex.source + "|" + separatorRegex.source + "$", "i"), "");
    }

    if (options.preserveCase) {
      return result;
    }

    return result.toLowerCase();
  },
  (string, options) => `${string}-${options?.locale}-${options?.separator}-${options?.preserveCase}`
);