index.js

const visit = require("unist-util-visit");
const twemoji = require("twemoji");

// https://reactnativecafe.com/emojis-in-javascript/#Conclusion
const EmojiRegExp = new RegExp(
  "(?:[\u2700-\u27bf]|(?:\ud83c[\udde6-\uddff]){2}|[\ud800-\udbff][\udc00-\udfff]|[\u0023-\u0039]\ufe0f?\u20e3|\u3299|\u3297|\u303d|\u3030|\u24c2|\ud83c[\udd70-\udd71]|\ud83c[\udd7e-\udd7f]|\ud83c\udd8e|\ud83c[\udd91-\udd9a]|\ud83c[\udde6-\uddff]|[\ud83c[\ude01-\ude02]|\ud83c\ude1a|\ud83c\ude2f|[\ud83c[\ude32-\ude3a]|[\ud83c[\ude50-\ude51]|\u203c|\u2049|[\u25aa-\u25ab]|\u25b6|\u25c0|[\u25fb-\u25fe]|\u00a9|\u00ae|\u2122|\u2139|\ud83c\udc04|[\u2600-\u26FF]|\u2b05|\u2b06|\u2b07|\u2b1b|\u2b1c|\u2b50|\u2b55|\u231a|\u231b|\u2328|\u23cf|[\u23e9-\u23f3]|[\u23f8-\u23fa]|\ud83c\udccf|\u2934|\u2935|[\u2190-\u21ff])"
);

module.exports = options => {
  const settings = options || {};
  function attributesCallback(rawText) {
    return {
      title: rawText
    };
  }
  function transformer(tree) {
    visit(tree, "text", node => {
      if (EmojiRegExp.test(node.value)) {
        const parsedNode = twemoji.parse(
          node.value,
          Object.assign({ attributes: attributesCallback }, settings)
        );
        node.type = "html";
        // Check if 'isReact: true' is specified in options
        if (settings.isReact) {
          node.value = parsedNode.replace(/class/g, "className");
        } else {
          node.value = parsedNode;
        }
      }
    });
  }

  return transformer;
};