How can I track which tab or content script a message came from? - firefox-addon

Question

In a Firefox add-on I need to track which tab messages are associated with. The content script will send data to the main.js. Later, when the user clicks the extension's button in the toolbar it will look for data associated with the active tab.
In Chrome extensions, when a message was received, I could ask which tab the message came from and track messages by the tab id. In Firefox, tabs have id's too, but there doesn't seem to be an easy way to access them from content scripts.

Answer 1

The answer depends on which way you are creating the content scripts. Below is an example main.js file for adding content scripts with PageMod.
var buttons = require('sdk/ui/button/action'),
pageMod = require('sdk/page-mod'),
data = require('sdk/self').data;
// Map of messages keyed by tab id
var messages = {};
pageMod.PageMod({
include: 'http://www.example.com',
contentScriptFile: [
data.url('my-script.js')
],
onAttach: function(worker){
// Get the tab id from the worker
var tabId = worker.tab.id;
// Save the message
worker.port.on('message', function(message){
messages[tabId] = message;
});
// Delete the messages when the tab is closed
// to prevent a memory leak
worker.on('detach', function(){
delete messages[tabId];
});
}
});
var button = buttons.ActionButton({
id: 'my-extension',
label: 'Example',
icon: {
'16': './icon-16.png',
'32': './icon-32.png',
'64': './icon-64.png'
},
onClick: function(state){
// Retrieve the message associated with the
// currently active tab, if there is one
var message = messages[tabs.activeTab.id];
// Do something with the message
}
});
I also recommend reading Content Scripts - Interacting with Page Scripts and Content Worker for a better understanding about what's going on and how to adapt it to your situation.