index.ts

type Options = {
  stripListLeaders?: boolean;
  listUnicodeChar: string | boolean;
  gfm?: boolean;
  useImgAltText?: boolean;
  preserveLinks?: boolean;
};

/**
 * @function removeMarkdown
 *
 * @description
 * Parse the markdown and returns a string
 *
 * @param markdown - The markdown string to parse
 * @param options - The options for the function
 *
 * @returns The parsed plain text
 */
const removeMarkdown = (
  markdown: string,
  options: Options = {
    listUnicodeChar: "",
  }
) => {
  options = options || {};
  options.listUnicodeChar = options.hasOwnProperty("listUnicodeChar")
    ? options.listUnicodeChar
    : false;
  options.stripListLeaders = options.hasOwnProperty("stripListLeaders")
    ? options.stripListLeaders
    : true;
  options.gfm = options.hasOwnProperty("gfm") ? options.gfm : true;
  options.useImgAltText = options.hasOwnProperty("useImgAltText")
    ? options.useImgAltText
    : true;
  options.preserveLinks = options.hasOwnProperty("preserveLinks")
    ? options.preserveLinks
    : false;

  let output = markdown || "";

  // Remove horizontal rules (stripListHeaders conflict with this rule, which is why it has been moved to the top)
  output = output.replace(/^(-\s*?|\*\s*?|_\s*?){3,}\s*$/gm, "");

  try {
    if (options.stripListLeaders) {
      if (options.listUnicodeChar)
        output = output.replace(
          /^([\s\t]*)([\*\-\+]|\d+\.)\s+/gm,
          options.listUnicodeChar + " $1"
        );
      else output = output.replace(/^([\s\t]*)([\*\-\+]|\d+\.)\s+/gm, "$1");
    }
    if (options.gfm) {
      output = output
        // Header
        .replace(/\n={2,}/g, "\n")
        // Fenced codeblocks
        .replace(/~{3}.*\n/g, "")
        // Strikethrough
        .replace(/~~/g, "")
        // Fenced codeblocks
        .replace(/`{3}.*\n/g, "");
    }
    if (options.preserveLinks) {
      // Remove inline links while preserving the links
      output = output.replace(/\[(.*?)\][\[\(](.*?)[\]\)]/g, "$1 ($2)");
    }
    output = output
      // Remove HTML tags
      .replace(/<[^>]*>/g, "")
      // Remove setext-style headers
      .replace(/^[=\-]{2,}\s*$/g, "")
      // Remove footnotes?
      .replace(/\[\^.+?\](\: .*?$)?/g, "")
      .replace(/\s{0,2}\[.*?\]: .*?$/g, "")
      // Remove images
      .replace(/\!\[(.*?)\][\[\(].*?[\]\)]/g, options.useImgAltText ? "$1" : "")
      // Remove inline links
      .replace(/\[(.*?)\][\[\(].*?[\]\)]/g, "$1")
      // Remove blockquotes
      .replace(/^\s{0,3}>\s?/g, "")
      .replace(/(^|\n)\s{0,3}>\s?/g, "\n\n")
      // Remove reference-style links?
      .replace(/^\s{1,2}\[(.*?)\]: (\S+)( ".*?")?\s*$/g, "")
      // Remove atx-style headers
      .replace(
        /^(\n)?\s{0,}#{1,6}\s+| {0,}(\n)?\s{0,}#{0,} {0,}(\n)?\s{0,}$/gm,
        "$1$2$3"
      )
      // Remove emphasis (repeat the line to remove double emphasis)
      .replace(/([\*_]{1,3})(\S.*?\S{0,1})\1/g, "$2")
      .replace(/([\*_]{1,3})(\S.*?\S{0,1})\1/g, "$2")
      // Remove code blocks
      .replace(/(`{3,})(.*?)\1/gm, "$2")
      // Remove inline code
      .replace(/`(.+?)`/g, "$1")
      // Replace two or more newlines with exactly two? Not entirely sure this belongs here...
      .replace(/\n{2,}/g, "\n\n");
  } catch (e) {
    console.error(e);

    return markdown;
  }
  return output;
};

export { removeMarkdown };