regenerator-runtime/runtime-module.js

// This method of obtaining a reference to the global object needs to be
// kept identical to the way it is obtained in runtime.js
var g =
  typeof global === "object" ? global :
  typeof window === "object" ? window :
  typeof self === "object" ? self : this;

// Use `getOwnPropertyNames` because not all browsers support calling
// `hasOwnProperty` on the global `self` object in a worker. See #183.
var hadRuntime = g.regeneratorRuntime &&
  Object.getOwnPropertyNames(g).indexOf("regeneratorRuntime") >= 0;

// Save the old regeneratorRuntime in case it needs to be restored later.
var oldRuntime = hadRuntime && g.regeneratorRuntime;

// Force reevalutation of runtime.js.
g.regeneratorRuntime = undefined;

module.exports = require("./runtime");

if (hadRuntime) {
  // Restore the original runtime.
  g.regeneratorRuntime = oldRuntime;
} else {
  // Remove the global property added by runtime.js.
  try {
    delete g.regeneratorRuntime;
  } catch(e) {
    g.regeneratorRuntime = undefined;
  }
}