new Worker("worker.js").postMessage("");

onmessage = function(e) {

  // Some examples APIs:    
    
  // HtmlUnit throw "org.htmlunit.corejs.javascript.EcmaError: ReferenceError: "URL" is not defined"
  new URL("http://example.com");

  // HtmlUnit throw "org.htmlunit.corejs.javascript.EcmaError: ReferenceError: "XMLHttpRequest" is not defined"
  new XMLHttpRequest();

  // HtmlUnit: undefined
  // Chrome: returns WorkerLocation for the script
  console.log(location);
}