Question

I’m doing a FireFox extensions. I have an array of URL’s. What I want is: redirect the page with document.location.href for all the URL’s that I have and then, with a XPath that I have, count the number of elements that the page has.

The problem is that I have to wait that the page load was finish before execute the count method with the XPath. This is my code:

var actualResult = 0;
actualResult = content.document.evaluate('count('+taskModeler.ui.getStatus()+')', content.document, null, XPathResult.NUMBER_TYPE, null).numberValue; 
for(var i=0; i<taskModeler.ui.getPageContent().length;i++) {
    content.document.location.href = taskModeler.ui.getPageContent()[i].getAttribute("href");
   //only if the page was loaded execute the next line

   actualResult+=content.document.evaluate('count('+taskModeler.ui.getStatus()+')',
       content.document, null, XPathResult.NUMBER_TYPE, null).numberValue; 
}

getPageContent() returns an array that contains a set of URL’s. For each of these URL’s I have to load the page to get acces to the document and then count the occurrences that returns the XPath. But if the page not was loaded the count method doesn’t work because returns the results of the actual page, not the page that was loaded in content.document.location.

How can I do that?

Answer 1

you need to use progress listener read this

const STATE_START = Components.interfaces.nsIWebProgressListener.STATE_START;  
const STATE_STOP = Components.interfaces.nsIWebProgressListener.STATE_STOP;  
  var myListener =  
 {  
 QueryInterface: function(aIID)  
 {  
  if (aIID.equals(Components.interfaces.nsIWebProgressListener) ||  
   aIID.equals(Components.interfaces.nsISupportsWeakReference) ||  
   aIID.equals(Components.interfaces.nsISupports))  
 return this;  
 throw Components.results.NS_NOINTERFACE;  
  },  

 onStateChange: function(aWebProgress, aRequest, aFlag, aStatus)  
 {  
 // If you use myListener for more than one tab/window, use  
 // aWebProgress.DOMWindow to obtain the tab/window which triggers the state change  
 f (aFlag & Components.interfaces.nsIWebProgressListener.STATE_IS_DOCUMENT) { 
 {  
     if(aFlag & STATE_STOP)  
 {  
   // This fires when the load page finishes  
 }  

 }  
     },  

 onLocationChange: function(aProgress, aRequest, aURI)  
  {  
  // This fires when the location bar changes; that is load event is confirmed  
  // or when the user switches tabs. If you use myListener for more than one tab/window,  
  // use aProgress.DOMWindow to obtain the tab/window which triggered the change.  
  },  

 // For definitions of the remaining functions see related documentation  
 onProgressChange: function(aWebProgress, aRequest, curSelf, maxSelf, curTot, maxTot) { },  
 onStatusChange: function(aWebProgress, aRequest, aStatus, aMessage) { },  
 onSecurityChange: function(aWebProgress, aRequest, aState) { }  
 }  

if u need more help tell me.