Find custom globals variables

custom_globals.js

{
    const iframe = document.createElement('iframe');
    document.body.append(iframe)
    setTimeout(()=>{ // wait some time until chrome adds console-accessible properties to the iframe too
      const customNames = Object.getOwnPropertyNames(window).filter(item => !(item in iframe.contentWindow) );
      const object = Object.create(null);
      customNames.forEach(name => object[name] = window[name] )
      console.log(object)
    },2000);
    'wait...';
}