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| | {{extdev}} | | {{extdev}} |
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| - | ==Progress Listeners== | |
| - | Progress listeners allow extensions to be notified of events associated with documents loading in the browser and with tab switching events. Progress listeners implement the <code>[http://www.xulplanet.com/references/xpcomref/ifaces/nsIWebProgressListener.html nsIWebProgressListener]</code> interface. | |
| | | | |
| - | Note that if you just want to execute your code each time a page loads, you can use an [[On Page Load|an easier method]]. | |
| | | | |
| - | ==Example== | + | Moved to [[http://developer.mozilla.org/en/docs/Code_snippets:Progress_Listeners|MDC]]. |
| - | <ol><li>Create an object which implements <code>nsIWebProgressListener</code>: | + | |
| - | <pre>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(aProgress, aRequest, aFlag, aStatus) | |
| - | { | |
| - | if(aFlag & STATE_START) | |
| - | { | |
| - | // This fires when the load event is initiated | |
| - | } | |
| - | if(aFlag & STATE_STOP) | |
| - | { | |
| - | // This fires when the load finishes | |
| - | } | |
| - | return 0; | |
| - | }, | |
| | | | |
| - | onLocationChange: function(aProgress, aRequest, aURI) | |
| - | { | |
| - | // This fires when the location bar changes i.e load event is confirmed | |
| - | // or when the user switches tabs | |
| - | return 0; | |
| - | }, | |
| - | | |
| - | // For definitions of the remaining functions see XulPlanet.com | |
| - | onProgressChange: function() {return 0;}, | |
| - | onStatusChange: function() {return 0;}, | |
| - | onSecurityChange: function() {return 0;}, | |
| - | onLinkIconAvailable: function() {return 0;} | |
| - | }</pre> | |
| - | </li> | |
| - | | |
| - | <li>Attach the progress listener to a <browser> or a <tabbrowser> element, e.g. for Firefox put the following code in a <code>load</code> listener of a main window: | |
| - | <pre>gBrowser.addProgressListener(myListener, | |
| - | Components.interfaces.nsIWebProgress.NOTIFY_STATE_DOCUMENT);</pre> | |
| - | | |
| - | The second argument is a [http://www.xulplanet.com/references/xpcomref/comps/c_appshellcomponentbrowserstatusfilter1.html status filter] which determines the type of events that will be received. All six progress handler functions must be defined, even if filters are used. | |
| - | </li> | |
| - | <li>Remember to call <code>removeProgressListener</code> in an <code>unload</code> event handler or earlier. | |
| - | </li> | |
| - | </ol> | |
| - | | |
| - | Remember to change <code>myListener</code> to an [[JavaScript coding guidelines|unique identifier]]. | |
| - | | |
| - | Also remember that if you're adding listeners inside a function, make sure to have a reference to your listener object that stays in memory (this is due to the required nsISupportsWeakReference interface). | |
| - | | |
| - | == Example: Getting notified when the value in Location Bar changes == | |
| - | A commonly asked question is how to get notified whenever the URL in the [[:Category:Location Bar|Location Bar]] (also known as address bar) changes. Using the following code, you will get notified when user navigates to another page (by clicking a link, using the back/forward button, by typing an address in the Location Bar, etc.) and also when user switches tabs. | |
| - | <pre> | |
| - | var myExt_urlBarListener = { | |
| - | 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; | |
| - | }, | |
| - | | |
| - | onLocationChange: function(aProgress, aRequest, aURI) | |
| - | { | |
| - | myExtension.processNewURL(aURI); | |
| - | }, | |
| - | | |
| - | onStateChange: function() {}, | |
| - | onProgressChange: function() {}, | |
| - | onStatusChange: function() {}, | |
| - | onSecurityChange: function() {}, | |
| - | onLinkIconAvailable: function() {} | |
| - | }; | |
| - | | |
| - | var myExtension = { | |
| - | oldURL: null, | |
| - | | |
| - | init: function() { | |
| - | // Listen for webpage loads | |
| - | gBrowser.addProgressListener(myExt_urlBarListener, | |
| - | Components.interfaces.nsIWebProgress.NOTIFY_STATE_DOCUMENT); | |
| - | }, | |
| - | | |
| - | uninit: function() { | |
| - | gBrowser.removeProgressListener(myExt_urlBarListener); | |
| - | }, | |
| - | | |
| - | processNewURL: function(aURI) { | |
| - | if (aURI.spec == this.oldURL) | |
| - | return; | |
| - | | |
| - | // now we know the url is new... | |
| - | alert(aURI.spec); | |
| - | this.oldURL = aURI.spec; | |
| - | } | |
| - | }; | |
| - | | |
| - | // Edit: for me on Firefox 2.0, I had to change "document" to "window" | |
| - | // for the following lines to work | |
| - | document.addEventListener("load", function() {myExtension.init()}, false); | |
| - | document.addEventListener("unload", function() {myExtension.uninit()}, false); | |
| - | </pre> | |
| | | | |
| | [[Category:Example code]] [[Category:JavaScript example code]] | | [[Category:Example code]] [[Category:JavaScript example code]] |
