Addon Sdk - Context-menu And Page-mod Workers

I have been working on a context-menu that communicates with a page mod and come up against an issue. I am able to send a communication with right click to the page / tab in view a

Solution 1:

Ran into this too. The Worker objects seem to stick around for some past pages (and reused when going Back and Forward in history). The solution is to listen to the pagehide and pageshow events so as to only keep the currently shown workers in the array:

var pageMod = require("sdk/page-mod");
vararray = require('sdk/util/array');

var pageWorkers = [];
pageMod.PageMod({
  onAttach: function(worker) {
      array.add(pageWorkers, worker);
      worker.on('pageshow', function() { array.add(pageWorkers, this); });
      worker.on('pagehide', function() { array.remove(pageWorkers, this); });
      worker.on('detach', function() { array.remove(pageWorkers, this); });
      // do other work.
  }
});

Note that array.add function takes care of not adding duplicates.

Solution 2:

Not sure I got your problem. The event you mentioned, detach, is also emitted when a the tab is reloaded:

const { add, remove } = require("sdk/util/array");
const workers = [];

require("sdk/page-mod").PageMod({
  include: "*",
  contentScript: "alert('executed')",
  onAttach: function(worker) {
    add(workers, worker);
    console.log('attached: ', workers.length);

    worker.on('detach', function() {
      remove(workers, worker);
      console.log('detached: ', workers.length);
    })
  }
});

When I reload the page the detach's listener is executed. Anyway, to check if a tab's associate to the worker is the active's tab you should be able to compare just the tab object: (workers[index].tab === tabs.activeTab). Notice also that in Add-on SDK 1.14 tabs have also the id property, so you can use it to identify themselves. And the for…in loop for index is not reccomended: https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Statements/for...in check the description section. I would rather use the for…of:

for (let worker of workers) { ... }

Solution 3:

ZERO is right, the event detach is emitted on reload. But when I open a different page in the same tab no detach-event is been emitted! So, i.e., when I have loaded some page A in tab 1 and click on a link which opens a different page B in the same tab 1 I have to detach the worker for page A manually(?)

var workers = [];    

require('page-mod').PageMod({
  include: '*',
  contentScriptWhen: 'end',
  contentScript: [require('self').data.url('bla.js')],
  onAttach: function(worker) {
    var w = workers.length;
    while (w--) {
      if (worker.tab === workers[w].tab) {
        workers.splice(w, 1);
        break;
      }
    }
    workers.push(worker);
    // other stuff
  }
});