A User Script to Block `disable-devtools`

block-disable-devtools.js

// ==UserScript==
// @name         Disable Anti-DevTools Mechanism
// @namespace    http://tampermonkey.net/
// @version      1.0
// @description  Prevents JavaScript from redirecting the page.
// @author       Ceshine Lee
// @match        *://*.example.com/*
// @grant        none
// @run-at       document-start
// ==/UserScript==

(function() {
    'use strict';

    console.log('User script to block anti-devtools is running!');

    window.addEventListener('beforeunload', function (e) {
        // Cancel the event
        e.preventDefault();
        // Chrome requires returnValue to be set to an empty string
        e.returnValue = '';
    });

    // Override the functions that cause page navigation.
    // We replace them with functions that do nothing except log to the console for debugging.
    window.history.back = function() { console.log('[UserScript] history.back() was blocked.'); };
    window.history.go = function() { console.log('[UserScript] history.go() was blocked.'); };

    // Instead of window.location.assign, we modify the prototype.
    // This is more robust and avoids the "read-only" error.
    Location.prototype.assign = function() {
        console.log('[UserScript] location.assign() was blocked.');
    };
    Location.prototype.replace = function() {
        console.log('[UserScript] location.replace() was blocked.');
    };
    
    // Disable setInterval to block the fallback attempts from disable-devtools
    // This is very effective but may break other site functionality.
    window.setInterval = function() { console.log('[UserScript] setInterval() was blocked.'); };
})();