title: What features are added to Javascript in the browser
body: <p>Things like the DOM and the XMLHttpRequest object is not part of any Ecmascript specification, if I've understood it correctly.</p>
  
  <p>I understand that the feature set vary between browser vendors and versions, but in general, what more Javascript features are available to us in a browser environment that are not part of any Ecmascript specification?</p>