How to extract number of currently opened tabs? - firefox

Question

I want to automatically count number of tabs that are open in Firefox so I can track this over time. It is not enough to get an add-on that displays current number in the browser.
From .sqlite tables Firefox saves for each profile I have not been able to decipher any table of currently opened tabs. I also looked for a column in the history table that tells whether page is currently open or not. Is this information available in the databases at all? If so, where is it stored? If not, how do add-ons like Tab Counter find this number?

Answer 1

Open the about:telemetry link in Firefox and click scalars tab from the sidebar menu. Alternatively, opening about:telemetry#scalars-tab_search=tab will take you directly to the scalars tab.
The browser.engagement.max_concurrent_tab_count key will show the number of tabs active for the session, but does not update when a tab is closed. Instead, if you want to update this value you will need to restart your browser.
The browser.engagement.tab_open_event_count key shows the current number of open tabs at a given time and is updated dynamically.

Answer 2

Online
Within a running Firefox session, it's easy to extract the data using the Mozilla Add-on API. I wrote a simple Tab Count Logger extension that does this, and saves the count to an SQLite database.
The relevant part of the code is:
const tabs = require("sdk/tabs");
const windows = require("sdk/windows").browserWindows;
console.log("Windows: " + windows.length + "; tabs: " + tabs.length);
Offline
Opened tabs are stored in sessionstore.js in the profile directory, not in SQLite. This file is JSON. A script to count tabs:
#!/usr/bin/env python3
# Count open tabs from a firefox profile
# Working directory is the root of a Firefox profile.
import json
j = json.loads(open("sessionstore.js", 'rb').read().decode('utf-8'))
def info_for_tab(tab):
try:
return (tab['entries'][0]['url'], tab['entries'][0]['title'])
except IndexError:
return None
except KeyError:
return None
def tabs_from_windows(window):
return list(map(info_for_tab, window['tabs']))
all_tabs = list(map(tabs_from_windows, j['windows']))
print('Statistics: {wins} windows, {tabs} total tabs'.format(wins=len(all_tabs), tabs=sum(map(len, all_tabs))))
After having saved this to ~/bin/firefox_count_tabs, you can get the information for all your profiles as in:
for i in ~/.mozilla/firefox/*.*; do test -d $i && (echo "== $i =="; cd $i; ~/bin/firefox_count_tabs ); done

Answer 3

The count will be shown on the exit confirm dialog - if you hadn't disable that 😂️
update 2022-11-02: only when you have only one window

Answer 4

#Xidus: History and bookmarks are stored in the places.sqlite. You cannot determine tabs and windows information here.tabs and windows information are stored in the sessionstore.js file.You can refer this links:
http://kb.mozillazine.org/sessionstore.js
http://forums.mozillazine.org/viewtopic.php?f=38&t=622036&start=60&p=12098147#p12098147

Answer 5

You can count tabs in the Browser Console (not Web Console) with:
gBrowser.tabs.length
The Browser Console is disabled by default. To enable it you can either:
Tick the option "Enable browser chrome and add-on debugging toolboxes" in the Web Developer Tools settings.
Go to about:config and search for devtools.chrome.enabled, and toggle it to true.
After that look for Browser Console in the More tools menu, or open the Developer Console with [CTRL]+[SHIFT]+J, and you can now enter the above.
option-1
option-2
[CTRL]+[SHIFT]+J