@leichtgewicht/esm2umd/index.mjs

Transforms ESM to UMD.

import babel from "@babel/core";
import transform from "@babel/plugin-transform-modules-commonjs";
import path from "path";

const filename = decodeURI(import.meta.url).replace(/^file:\/\/(\/(\w+:))?/, '$2').replace(/\//g, path.sep);

const wrapper = `// GENERATED FILE. DO NOT EDIT.
var %NAME% = (function(exports) {
  %CODE%
  return "default" in exports ? exports.default : exports;
})({});
if (typeof define === 'function' && define.amd) define([], function() { return %NAME%; });
else if (typeof module === 'object' && typeof exports==='object') module.exports = %NAME%;
`;

export default function esm2umd(moduleName, esmCode, options = {}) {
  if (!options.importInterop) options.noInterop = true;
  const umdCode = babel.transform(esmCode, {
    plugins: [
      [ transform, options ]
    ]
  }).code.trim().replace(/decodeURI\(import\.meta\.url\)\.replace\(\/\^file\:\\\/\\\/\(\\\/\(\\w\+\:\)\)\?\/, \'\$2'\)\.replace\(\/\\\/\/g, _?path\.sep\)/g, '__filename');
  if (moduleName) {
    return wrapper
      .replace(/%NAME%/g, moduleName)
      .replace("%CODE%", umdCode.replace(/\n/g, "\n  ").trimRight());
  }
  return umdCode;
}

esm2umd.filename = filename