who cares about blur

README.md

Who cares about blur?

Problem: Learning management systems are picky about what tabs you have open, and if you're switching between tabs during an exam.

Solution: This script completly disables any detection of the window being blurred and suppresses any events.

This script can be installed via Tampermonkey and is tested to work on Firefox and Chrome.

ignore-blur.user.js

// ==UserScript==
// @name         who cares about blur
// @namespace    https://github.com/e9x
// @version      1.0.0
// @description  Prevent pages from detecting when they lose focus
// @author       e9x
// @homepageURL  https://github.com/e9x
// @match        *://*/*
// @grant        none
// @run-at       document-start
// ==/UserScript==

// IMPORTANT STEPS FOR TAMPERMONKEY
// 1. Go to Tampermonkey Dashboard.
// 2. Click on settings.
// 3. Change Config mode to Advanced.
// 4. Scroll to the bottom of the dashboard and find "Experimental". Change Inject Mode to Instant.


// PROTECTION #1: INVOKE ORIGINAL HANDLERS WITH `this` TO THROW ORIGINAL ERRORS
// TODO: PROTECT FUNCTION SOURCE WITH HELPERS

// PROPERTIES

const STATE_VISIBLE = "visible";

const visibilityState = Object.getOwnPropertyDescriptor(Document.prototype, "visibilityState");

Object.defineProperty(Document.prototype, "visibilityState", {
  configurable: true,
  enumerable: true,
  get() {
    // PROTECTION #1
    Reflect.apply(visibilityState.get, this, []);
    return STATE_VISIBLE;
  },
});

const webkitVisibilityState = Object.getOwnPropertyDescriptor(Document.prototype, "webkitVisibilityState");

Object.defineProperty(Document.prototype, "webkitVisibilityState", {
  configurable: true,
  enumerable: true,
  get() {
    // PROTECTION #1
    Reflect.apply(webkitVisibilityState.get, this, []);
    return STATE_VISIBLE;
  },
});

const hidden = Object.getOwnPropertyDescriptor(Document.prototype, "hidden");

Object.defineProperty(Document.prototype, "hidden", {
  configurable: true,
  enumerable: true,
  get() {
    // PROTECTION #1
    Reflect.apply(hidden.get, this, []);
    // always never hidden
    return false;
  },
});

// FUNCTIONS

const { hasFocus } = Document.prototype;

Document.prototype.hasFocus = function () {
  // PROTECTION #1
  Reflect.apply(hasFocus, this, []);
  // ermm we're always focused
  return true;
}

// WINDOW EVENTS

window.addEventListener("blur", (e) => {
  e.preventDefault();
  e.stopPropagation();
  e.stopImmediatePropagation();
});

window.addEventListener("focus", (e) => {
  e.preventDefault();
  e.stopPropagation();
  e.stopImmediatePropagation();
});

// DOM EVENTS

document.addEventListener("visibilitychange", (e) => {
  e.preventDefault();
  e.stopPropagation();
  e.stopImmediatePropagation();
});

// MOUSE EVENTS

const { addEventListener } = EventTarget.prototype;

const mouseEvents = ["mousemove", "mouseenter", "mouseleave", "mouseover", "mouseout"];

EventTarget.prototype.addEventListener = function(type, callback, options) {
  if (mouseEvents.includes(type)) {
    console.log("ermmm no mouse event!");
    return;
  }

  return Reflect.apply(addEventListener, this, [type, callback, options]);
}

for (const event of mouseEvents) {
  const prop = "on" + event;

  // define the handler on window & element protos
  for (const proto of [HTMLElement.prototype, window]) {
    const { get, set } = Object.getOwnPropertyDescriptor(proto, prop);
    let v = null;
    Object.defineProperty(proto, prop, {
      configurable: true,
      enumerable: true,
      get() {
        // PROTECTION #1
        Reflect.apply(get, this, []);
        return v;
      },
      set(value) {
        // PROTECTION #1
        Reflect.apply(get, this, []);
        if (typeof value === "function") v = value;
        else v = null;
      },
    });
  }
}