Block Real AdSense.
Four layers deep.

Patches document.createElement so that any <script> element trying to set its src to adsbygoogle.js gets the assignment silently dropped. The browser never starts a network request — not even a DNS lookup.

document.createElement = function(tag) {
  const el = native(tag)
  if (tag === 'script') {
    Object.defineProperty(el, 'src', {
      set(value) {
        if (isAdsenseUrl(value)) return // blocked
        nativeSrc.set.call(this, value)
      }
    })
  }
  return el
}

On startup, querySelectorAll scans for any adsbygoogle.js scripts already in the DOM — injected server-side or by a previous script. Each is given a blocked MIME type, its src is cleared, and it is removed before it can run.

document
  .querySelectorAll('script[src*="adsbygoogle.js"]')
  .forEach(el => {
    el.type = 'javascript/blocked'
    el.src  = ''
    el.remove()
  })

A MutationObserver watches the full document tree after load. Scripts injected via innerHTML, third-party tag managers, or lazy imports are caught the moment they enter the DOM and blocked before the browser fetches the URL.

new MutationObserver(mutations => {
  for (const { addedNodes } of mutations)
    for (const node of addedNodes)
      if (isBlockableScript(node))
        block(node) // type=blocked, src='', remove()
}).observe(document.documentElement, {
  childList: true, subtree: true
})

Even if adsbygoogle.js fully loads and executes, it cannot replace window.adsbygoogle. An Object.defineProperty getter locks the property to the simulator's queue permanently. Any write attempt is swallowed with a console message.

Object.defineProperty(window, 'adsbygoogle', {
  get() { return simulatorQueue },
  set() {
    // real AdSense tries to replace — blocked
    console.info('blocked attempt to replace')
  },
  configurable: true
})