The single web page application featured in this tutorial web page is a dark-web-hosted software application which checks whether another dark-web-hosted web page (namely, the root-level directory of karbytes’ largest .onion website) is online once every sixty seconds and keeps a log displaying information about the most recent one hundred polls (while total success and failure counts continue to incrementing indefinitely (while the polling application web browser window is open and running) and such that the oldest record in the table is removed to make room for each new record at the bottom of the table after the table becomes one hundred rows tall). In order to keep the polling application running instead of pausing while the respective Tor browser tab is not immediately open on mobile devices (i.e. not the active browser tab or application), the polling application enables the user to press a button which starts playing three sound files simultaneously for the duration of the polling session (such that each sound file is playing at an audible volume and such that each sound file has a different play duration (which enables the session to stay active for an indefinitely long time due to the fact that the sound files do not stop and restart at the same times)).

Note that a live version of the ONION_WEB_PAGE_AVAILABILITY_LOGGER application is available to try using immediately from the Tor web browser at the following (dark) web address: http://qkbrwfubnh4knc6kkhx6uepccavpwezdf2al7w2quepe3qociegsi3yd.onion/KARBYTES_BLOG_APPS/ONION_WEB_PAGE_AVAILABILITY_LOGGER/onion_web_page_availability_logger.html

Note that the live web application whose Uniform Resource Locator is displayed above is hosted from karbytes’ own personal stationary closet server and so is the .onion web page which the polling application monitors minute-by-minute (while the polling application is running). Unlike karbytes’ GitHub-hosted web applications, karbytes’ dark web server hosted web applications might not function as reliably and as efficiently as their light web counterparts (but karbytes makes an effort to always keep its dark web server running and accessible to the general public via the Tor network as often as possible).

To view hidden text inside of the preformatted text boxes below, scroll horizontally.

Unlike most of karbytes’ older software engineering portfolio applications, ONION_WEB_PAGE_AVAILABILITY_LOGGER consists of only one source code file and generates no accompanying output file(s). The three (MP3) sound files which the ONION_WEB_PAGE_AVAILABILITY_LOGGER application uses are part of an older dark web application named SOUND_TRACK_LOOP_COUNTER_TWO.

The following Hyper-Text-Markup-Language (HTML) code defines the user interface component of the ONION_WEB_PAGE_AVAILABILITY_LOGGER web page application. Copy the HTML code from the source code file which is linked below into a text editor and save that file as onion_web_page_availability_logger.html. Use a web browser such as Firefox to open that HTML file.

(Note that angle brackets which resemble HTML tags (i.e. an “is less than” symbol (i.e. ‘<‘) followed by an “is greater than” symbol (i.e. ‘>’)) displayed on this web page have been replaced (at the source code level of this web page) with the Unicode symbols U+003C (which is rendered by the web browser as ‘<‘) and U+003E (which is rendered by the web browser as ‘>’). That is because the WordPress web page editor or web browser interprets a plain-text version of an “is less than” symbol followed by an “is greater than” symbol as being an opening HTML tag (which means that the WordPress web page editor or web browser deletes or fails to display those (plain-text) inequality symbols and the content between those (plain-text) inequality symbols)).

<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>.onion Fetch Monitor (with Pruning)</title> <style> body { font-family: sans-serif; padding: 20px; } table { border-collapse: collapse; width: 100%; margin-top: 20px; } th, td { border: 1px solid #333; padding: 8px; text-align: left; } th { background-color: #eee; } .stats { margin-top: 10px; font-weight: bold; } #keep_session_active_button { background: #00ff00; color: #000000; border-color: #00ff00; border-width: 1px; border-style: solid; border-radius: 5px; padding: 10px; appearance: none; font-family: monospace; font-size: 16px; } #keep_session_active_button:hover { background: #00ffff; border-color: #00ffff; } </style> </head> <body>  <h1>.onion Page Fetch Monitor</h1> <p><em>Determine whether or not <a style="background: #000000;color: #00ffff" href="http://qkbrwfubnh4knc6kkhx6uepccavpwezdf2al7w2quepe3qociegsi3yd.onion/" target="_blank" rel="noopener">a particular .onion web page</a> is discoverable on the World Wide Web at a particular time.</em></p> <p><em>Log the most recent 100 instances of polling that .onion web page once per every 60 seconds (until this browser window is closed).</em></p> <p><em>(Note that <a style="background: #000000;color: #00ff00" href="http://qkbrwfubnh4knc6kkhx6uepccavpwezdf2al7w2quepe3qociegsi3yd.onion/KARBYTES_BLOG_APPS/ONION_WEB_PAGE_AVAILABILITY_LOGGER/onion_web_page_availability_logger.html" target="_blank" rel="noopener">this web page application</a> must be hosted from a dark web server in order to work).</em></p> <p><em>(Note also that this web page application must be run via a dark web browser such as Tor).</em></p> <p style="background:#ffff00"><em>(Documentation: <a style="background: #000000;color: #00ff00" href="https://karbytesforlifeblog.wordpress.com/onion_web_page_availability_logger/" target="_blank" rel="noopener">https://karbytesforlifeblog.wordpress.com/onion_web_page_availability_logger/</a>).</em></p> <p style="background:#00ffff">Polling: <code>http://qkbrwfubnh4knc6kkhx6uepccavpwezdf2al7w2quepe3qociegsi3yd.onion/</code> every 60 seconds.</p>  <p><em>(To prevent the script in this web page from haulting due to it not being the active application window on a mobile device, click the button below to start playing sound tracks with staggered play durations).</em></p> <p><input type="button" id="keep_session_active_button" value="keep_session_active()" onclick="keep_session_active()"></p>  <div class="stats"> <p>Total Attempts: <span id="totalAttempts">0</span></p> <p>Successes: <span id="successCount">0</span></p> <p>Failures: <span id="failureCount">0</span></p> <p>Success Rate: <span id="successRate">0%</span></p> </div>  <table id="logTable"> <thead> <tr> <th>ISO Timestamp</th> <th>Unix Epoch (ms)</th> <th>Status</th> <th>Notes</th> </tr> </thead> <tbody></tbody> </table>  <script> /** * The JavaScript code which follows is intended to keep this Tor browser tab active * rather than going dormant while that browser tab is treated by the operating system (OS) * as a background process on mobile devices. * * On mobile devices such as an Android smartphone, only one browser tab and only one * non-OS software application can be actively featured in the user's "viewport" per * instant. By contrast, on more fully-featured machines such as a Ubuntu laptop computer, * multiple browser tabs and multiple non-OS software applications can be running simultaneously * inside of one "viewport" (i.e. user experience instant). */ // List of audio file URLs const file_path_root = 'http://qkbrwfubnh4knc6kkhx6uepccavpwezdf2al7w2quepe3qociegsi3yd.onion/KARBYTES_BLOG_APPS/SOUND_TRACK_LOOP_COUNTER_TWO/'; const soundTracks = [ file_path_root + 'karbytes_drums_20_october_2023.mp3', // 200 seconds file_path_root + 'frogs_croaking_in_castro_valley_california_21_april_2022.mp3', // 16 seconds file_path_root + 'karbytes_guitar_castro_valley_california_12_december_2022.mp3', // 109 seconds ]; // Create and configure audio elements const audioElements = soundTracks.map(src => { const audio = new Audio(src); audio.loop = true; // audio.volume = 0.0; // Silent playback (full volume is 1.0) audio.volume = 1.0; // Volume is turned to 100% for debugging purposes. Never mind! Volume is turned up for functional purposes. The browser seems to treat zero volume sound file plays as non-existent processes. return audio; }); // Function to start playback on user interaction function startPlayingSilentSoundTracks() { audioElements.forEach(audio => { audio.play().catch(err => { console.warn("Failed to play track:", err); }); }); } /** * "Wrapper function" has a name suggesting its purpose. * * (For security reasons, a user-initiated action is required * to start the indefinitely long session created by multiple * audio files playing simultaneously on indefinitely many loops). * * (Each sound file has a unique duration (with respect to each of the three sound files * referenced by this HTML file) in order to ensure that the sound files start and stop * playing at different points in the time this HTML file is opened as a single web browser tab * so that there is no gap of "silence" (if the volumes of those sound tracks are set to audible) * while that browser tab is open (i.e. exists)). * * IMPORTANT UPDATE: The volume for the sound files has been turned up to 100% due to the fact * that the browser seems to treat the sound files like they are not being played if their volumes * are muted. (Hence, the function being called by this wrapper function is not actually playing silent * sound files in this configuration (but this application's source file can be downloaded and modified * to use genuinely silent audio files (i.e. sound files which consist of only silence even when their volumes * are turned up to maximum volume))).a */ function keep_session_active() { startPlayingSilentSoundTracks(); } /************************************************************************************************************************** * The code block above this comment is supposed to be above the code blocks below this comment. * That is because the code block above this comment defines variables used by the code blocks below this comment. * * This comment applies to a line of code which was commented out in visitPage(). **************************************************************************************************************************/ /** * The Uniform Resource Locator (URL) of the .onion web page being polled once per minute. * This is not the URL of the .onion web page doing that polling. */ const targetUrl = "http://qkbrwfubnh4knc6kkhx6uepccavpwezdf2al7w2quepe3qociegsi3yd.onion/"; // duration of time between each successive pull. const intervalMilliseconds = 60 * 1000; // mutable program variables let totalAttempts = 0; let successCount = 0; let failureCount = 0; const maxRows = 100; function updateStats() { document.getElementById("totalAttempts").textContent = totalAttempts; document.getElementById("successCount").textContent = successCount; document.getElementById("failureCount").textContent = failureCount; const successRate = totalAttempts > 0 ? ((successCount / totalAttempts) * 100).toFixed(2) + "%" : "0%"; document.getElementById("successRate").textContent = successRate; } function logResult(isoTime, epochTime, status, notes) { const tableBody = document.getElementById("logTable").querySelector("tbody"); // Prune oldest row if over max if (tableBody.rows.length >= maxRows) { tableBody.deleteRow(0); } const row = document.createElement("tr"); [isoTime, epochTime, status, notes].forEach(text => { const cell = document.createElement("td"); cell.textContent = text; row.appendChild(cell); }); tableBody.appendChild(row); } // This function is called when the web page is initially loaded by the web browser. async function visitPage() { // startPlayingSilentSoundTracks(); // Prevent the functions in this web page from haulting while the respective browser tab exists. const now = new Date(); const isoTime = now.toISOString(); // ISO 8601 time stamp formatting (International Organization for Standardization) const epochTime = now.getTime(); // milliseconds since Unix Epoch (midnight on 01_JANUARY_1990 Coordinated Universal Time (UTC)) totalAttempts++; try { const response = await fetch(targetUrl + "?t=" + epochTime, { method: "GET", mode: "no-cors", cache: "no-store" }); successCount++; logResult(isoTime, epochTime, "Attempted", `Response type: ${response.type}`); } catch (error) { failureCount++; logResult(isoTime, epochTime, "Failed", error.toString()); } updateStats(); } visitPage(); // Initial attempt setInterval(visitPage, intervalMilliseconds); </script> </body> </html>

ONION_WEB_PAGE_AVAILABILITY_LOGGER Interface (after clicking keep_session_alive())

The screenshot image below depicts a use case of the ONION_WEB_PAGE_AVAILABILITY_LOGGER application in which both successes (denoted by the application as Attempted) and failures (i.e. denoted as Failed) occurred.

The failures resulted from karbytes deliberately closing the laptop computer which was serving the .onion web page which ONION_WEB_PAGE_AVAILABILITY_LOGGER was attempting to check the availability of. Once karbytes opened the .onion serving laptop again and restarted the Tor and Apache services on that server laptop, ONION_WEB_PAGE_AVAILABILITY_LOGGER resumed logging successful availability attempts of the target .onion web page.

Note that, because the JavaScript code which controls the ONION_WEB_PAGE_AVAILABILITY_LOGGER application is executed entirely on the client-side instead of on the server-side of the client-server interaction, the application can continue running offline provided that the application web page is not refreshed.

(Note that the following screenshot has a spelling error (i.e. “bieng” instead of “being”) due to the fact that the screenshot was taken of a version of this application which is functionally identical to the latest version of this application but which has that spelling error and fewer code comments. The spelling error in the HTML file has since been corrected).

This web page was last updated on 13_JULY_2025. The content displayed on this web page is licensed as PUBLIC_DOMAIN intellectual property.