XMLHttpRequest - freeing after use?

I'm writing a browser app that would be entirely AJAX-driven (first time in my life), that means: - it will be one page staying in the browser, loading program components as needed - browser history will be, well, none. - page will not be refreshed at all My concern is what should I do about XMLHttpRequests, since I'm primarily C++ programmer, being taught that when you write a statement like ``` x = new XMLHttpRequest(); ``` you need to `delete` it afterwards. This question is entirely about memory management, whether this object, allocated with `new` stays in memory, even after it finishes it's "cycle" with readyState == 4 or is somehow released, freed, whatchacallit? Honestly, I have no idea at what point could it be freed, since the script creating these will be in HEAD and sit there potentially whole workday. Whether should I: - create one or several, reused objects of type XMLHttpRequest, program the app so that it won't need any more than this limit, - or it doesn't matter and I can allocate as many new XMLHttpRequests as I like? Please include in your answers at what point and WHY those objects would be deleted, if they would at all, considering that the "frame" of my webpage will stay. Hope I made this question clear and thanks for any insightful answers. EDIT: Consider code (I removed many lines that were checking for unexpected return values for brevity) of an `onClick` event handler, that creates XMLHttpRequest and sends it: ``` function submitme(){ var p = document.getElementById('p'); //a text field being sent to server if(typeof p!='undefined' && p!=null){ if(p.value!=""){ //here XMLHttpRequest is created, this function //returns exactly object of this type or false, when failed var xhr=createXmlHttpRequestObject(); if(xhr!=false){ xhr.open("POST", "blablabla.php", true); xhr.onreadystatechange=function(){ if(xhr.readyState==4){ if(xhr.status==200){ //result will be posted in this div below var adiv = document.getElementById('resultdiv'); //extract the XML retrieved from the server xmlResponse = xhr.responseXML; //obtain the document element (the root element) of the XML structure xmlDocumentElement = xmlResponse.documentElement; //get the response text if(typeof adiv !='undefined' && adiv != null){ adiv.innerHTML=xmlDocumentElement.childNodes[0].firstChild.nodeValue; } }//end xhr.status }//end xhr.readyState };//end xhr.onreadystatechange xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded"); xhr.send(p.value); }//end xhr!=false }//end p.value!="" }//end typeof p!='undefined' }//end submitme() ``` When XMLHttpRequest object instance is created, if this handler is fired, it is referenced once by `xhr` variable until handler finishes to execute. At this point there are how many references to this object instance? If I understand articles linked in your answers correctly, the answer should be none, and browser just waits for this request to turn `readystate==4`, finish executing `onreadystatechange` function and object is unreachable? Please confirm.