Activity Manager examples
r;1"].getservice(nsiam); let process = components.classes["@mozilla.org/activity-process;1"].createinstance(nsiap); // assuming folder is an instance of nsimsgfolder interface // localization is omitted, initiator is not provided process.init("processing folder: " + folder.prettiestname, null); // note that we don't define a custom icon, default process icon // will be used process.contexttype = "account"; // group this activity by account process.contextobj = folder.server; // account in question gactivitymanager.addactivity(process); // step 2: showing some progress let percent = 50; process.setprogress(percent, "junk processing 25 of 50 messages", 25, 50); // step 3: removing the process and adding an event using process' attributes process.state = components.interfaces.nsi...
...s.state_completed; gactivitymanager.removeactivity(process.id); let event = components.classes["@mozilla.org/activity-event;1"].createinstance(nsiae); // localization is omitted, initiator is omitted event.init(folder.prettiestname + " is processed", null, "no junk found", process.starttime, // start time date.now()); // completion time event.contexttype = process.contexttype; // optional event.contextobj = process.contextobj; // optional gactivitymanager.addactivity(event); showing a user-defined activity with cancel capability (javascript) this sample improves the previous one by providing an nsiactivitycancelhandler to allow the user to cancel the process.
...} sendercontextdisplayhelper.prototype = { getcontextdisplaytext: function(contexttype, contextobj) { // in this particular example we know that contexttype is "sender" // since we also pass the contexttype along with the contextobject // in some cases, one helper can be registered for a group of context types // we know that the context object is the author of the message // localization is omitted return "messages coming from " + contextobj.surname + ", " + co...
...let process = new nsactprocess("processing folder: " + folder.prettiestname, gjunkprocessor); process.cancelhandler = new canceljunkprocess(); // folder is being filtered/processed process.addsubject(folder); process.contexttype = "sender"; // assuming msg is an instance of nsimsghdr process.contextobj = msg.author; ...

HTMLCanvasElement.getContext() - Web APIs
later calls to this method on the same canvas element return the same drawing context instance as was returned the last time the method was invoked with the same contexttype argument.
... to get a different drawing context object you need to pass a different contexttype or call the method on a different canvas element.
... syntax var ctx = canvas.getcontext(contexttype); var ctx = canvas.getcontext(contexttype, contextattributes); parameters contexttype is a domstring containing the context identifier defining the drawing context associated to the canvas.
... if the contexttype doesn't match a possible drawing context, null is returned.

OffscreenCanvas.getContext() - Web APIs
syntax offscreen.getcontext(contexttype, contextattributes); parameters contexttype is a domstring containing the context identifier defining the drawing context associated to the canvas.
... if the contexttype doesn't match a possible drawing context, null is returned.