nsIWebProgressListener

nsIWebProgress describes the parent-child relationship of nsIWebProgress instances.

Method overview

Constants

State transition flags

These flags indicate the various states that requests may transition through as they are being loaded. These flags are mutually exclusive.

For any given request, onStateChange() is called once with the STATE_START flag, zero or more times with the STATE_TRANSFERRING flag or once with the STATE_REDIRECTING flag, and then finally once with the STATE_STOP flag.

State type flags

These flags further describe the entity for which the state transition is occurring. These flags are not mutually exclusive (that is an onStateChange() event may indicate some combination of these flags).

State modifier flags

These flags further describe the entity for which the state transition is occurring. These flags are NOT mutually exclusive (that is an onStateChange() event may indicate some combination of these flags).

State security flags

These flags describe the security state reported by a call to the onSecurityChange() method. These flags are mutually exclusive.

Security strength flags

These flags describe the security strength and accompany STATE_IS_SECURE in a call to the onSecurityChange() method. These flags are mutually exclusive.

These flags are not meant to provide a precise description of data transfer security. These are instead intended as a rough indicator that may be used to, for example, color code a security indicator or otherwise provide basic data transfer security feedback to the user.

State identity flags

These flags describe the level of identity verification in a call to the onSecurityChange() method.

Location Change flags

Methods

onLocationChange()

Called when the location of the window being watched changes. This is not when a load is requested, but rather once it is verified that the load is going to occur in the given window. For instance, a load that starts in a window might send progress and status messages for the new site, but it will not send the onLocationChange until we are sure that we are loading this new page here. Another example: the loading of a PDF or Flash file might not not send onLocationChange if the document is handed off to a third-party tool rather than being loaded into the browser.

void onLocationChange(
  in nsIWebProgress aWebProgress,
  in nsIRequest aRequest,
  in nsIURI aLocation,
  [optional] in unsigned long aFlags
);

Parameters

aWebProgress

The nsIWebProgress instance that fired the notification.

aRequest

The associated nsIRequest. This may be null in some cases.

aLocation

The URI of the location that is being loaded.

aFlags

This is a value which explains the situation or the reason why the location has changed. Optional from Gecko 11

onProgressChange()

Notification that the progress has changed for one of the requests associated with aWebProgress. Progress totals are reset to zero when all requests in aWebProgress complete (corresponding to onStateChange() being called with aStateFlags including the STATE_STOP and STATE_IS_WINDOW flags).

void onProgressChange(
  in nsIWebProgress aWebProgress,
  in nsIRequest aRequest,
  in long aCurSelfProgress,
  in long aMaxSelfProgress,
  in long aCurTotalProgress,
  in long aMaxTotalProgress
);

Parameters

aWebProgress

The nsIWebProgress instance that fired the notification.

aRequest

The nsIRequest that has new progress.

aCurSelfProgress

The current progress for aRequest.

aMaxSelfProgress

The maximum progress for aRequest.

aCurTotalProgress

The current progress for all requests associated with aWebProgress.

aMaxTotalProgress

The total progress for all requests associated with aWebProgress.

onSecurityChange()

Notification called for security progress. This method will be called on security transitions (for example HTTP -> HTTPS, HTTPS -> HTTP, FOO -> HTTPS) and after document load completion. It might also be called if an error occurs during network loading.

void onSecurityChange(
  in nsIWebProgress aWebProgress,
  in nsIRequest aRequest,
  in unsigned long aState
);

Parameters

aWebProgress

The nsIWebProgress instance that fired the notification.

aRequest

The nsIRequest that has new security state.

aState

A value composed of the Security State Flags and the Security Strength Flags listed above. Any undefined bits are reserved for future use.

onStateChange()

Notification indicating the state has changed for one of the requests associated with aWebProgress.

void onStateChange(
  in nsIWebProgress aWebProgress,
  in nsIRequest aRequest,
  in unsigned long aStateFlags,
  in nsresult aStatus
);

Parameters

aWebProgress

The nsIWebProgress instance that fired the notification.

aRequest

The nsIRequest that has changed state. This parameter may be null.

aStateFlags

Flags indicating the new state. This value is a combination of one of the State Transition Flags and one or more of the State Type Flags defined above. Any undefined bits are reserved for future use.

aStatus

Error status code associated with the state change. This parameter should be ignored unless aStateFlags includes the STATE_STOP bit. The status code indicates success or failure of the request associated with the state change.

Note: aStatus may be a success code even for server generated errors, such as the HTTP 404 File Not Found error. In such cases, the request itself should be queried for extended error information (for example for HTTP requests see nsIHttpChannel.

onStatusChange()

Notification that the status of a request has changed. The status message is intended to be displayed to the user (for example, in the status bar of the browser).

void onStatusChange(
  in nsIWebProgress aWebProgress,
  in nsIRequest aRequest,
  in nsresult aStatus,
  in wstring aMessage
);

Parameters

aWebProgress

The nsIWebProgress instance that fired the notification.

aRequest

The nsIRequest that has new status.

aStatus

This value is not an error code. Instead, it is a numeric value that indicates the current status of the request. This interface does not define the set of possible status codes.

Note: Some status values are defined by nsITransport and nsISocketTransport.

aMessage

Localized text corresponding to aStatus.

Example

The nsIWebProgressListener for each tab:

• gBrowser.mTabProgressListener can be used in the parent to listen for most nsIWebProgressListener events, but in browser code, will not have access to the nsIWebProgress's DOMWindow property. See the example below on how to use an nsIWebProgressListener in a frame script to get access to the DOM Window.
• This example here shows you how to detect what flags are popping up where. It puts the messages into the Browser Console.

  /**
   * This example assumes that it's being run within the context of a browser
   * window, and uses a frame script that will be loaded into every
   * browser tab.
   */
  let mm = window.getGroupMessageManager("browsers");
  mm.loadFrameScript("chrome://path/to/some/example-framescript.js", true);
  mm.addMessageListener("MyAddonMessage", (message) => {
    let data = message.data;
    let browser = message.target;
    let outerWindowID = data.outerWindowID;
    // browser is now the <xul:browser> that saw the web progress activity
    // occur. If you need to hold onto an identifier for whichever frame
    // (be it the top-level, or a subframe) was using the WebProgress, use
    // the outerWindowID. This can be communicated back down to the content
    // in order to do send a command to a particular DOM Window.
    Cu.reportError("Saw: " + data.name + " -- passing: " + JSON.stringify(data));
  });
  /**
   * Below is the contents of example-framescript.js
   */
  const {classes: Cc, interfaces: Ci, utils: Cu} = Components;
  Cu.import("resource://gre/modules/XPCOMUtils.jsm");
  var myListener = {
      QueryInterface: XPCOMUtils.generateQI(["nsIWebProgressListener",
                                             "nsISupportsWeakReference"]),
      onStateChange: function(aWebProgress, aRequest, aFlag, aStatus) {
          let win = aWebProgress.DOMWindow;
          let outerWindowID = win.QueryInterface(Ci.nsIInterfaceRequestor)
                                 .getInterface(Ci.nsIDOMWindowUtils)
                                 .outerWindowID; 
          sendAsyncMessage("MyAddonMessage", {
              name: "onStateChange",
              flag: aFlag,
              status: aStatus,
          });
      },
      onLocationChange: function(aProgress, aRequest, aURI, aFlag) {
          let win = aWebProgress.DOMWindow;
          let outerWindowID = win.QueryInterface(Ci.nsIInterfaceRequestor)
                                 .getInterface(Ci.nsIDOMWindowUtils)
                                 .outerWindowID;
          sendAsyncMessage("MyAddonMessage", {
              name: "onLocationChange",
              outerWindowID: outerWindowID,
              uri: aURI.spec,
              charSet: aURI.charSet,
              flag: aFlag,
          });
      },
      // 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) {}
  }
  let filter = Cc["@mozilla.org/appshell/component/browser-status-filter;1"]
                 .createInstance(Ci.nsIWebProgress);
  filter.addProgressListener(myListener, Ci.nsIWebProgress.NOTIFY_ALL);
  let webProgress = docShell.QueryInterface(Ci.nsIInterfaceRequestor)
                            .getInterface(Ci.nsIWebProgress);
  webProgress.addProgressListener(filter, Ci.nsIWebProgress.NOTIFY_ALL);

• XULBrowserWindow.onStateChange (etc.)
• reporterListener.onLocationChange

See also

• nsIWebProgressListener2