dataLayer Integrity Monitor

dataLayerMonitor.js

(function protectDataLayer() {
  window._internalDataLayer = window.dataLayer || [];

  //  Wrap the array in a Proxy to detect internal changes
  const dataLayerProxy = new Proxy(window._internalDataLayer, {
    set(target, prop, value, receiver) {
      console.log(`[dataLayer] Change detected: "${prop}" set to`, value);
      return Reflect.set(target, prop, value, receiver);
    },
    get(target, prop, receiver) {
      const value = Reflect.get(target, prop, receiver);

      // Detect mutating methods like push, pop, splice, etc.
      if (typeof value === 'function' && ['pop','shift','unshift','splice','sort','reverse'].includes(prop)) {
        return function (...args) {
          console.log(`[dataLayer] Method "${prop}" called with`, args);
          return value.apply(target, args);
        };
      }
      return value;
    }
  });

  // 3️⃣ Protect the variable itself from being overwritten
  Object.defineProperty(window, 'dataLayer', {
    configurable: true,
    enumerable: true,
    get() {
      return dataLayerProxy;
    },
    set(newValue) {
      console.log('[dataLayer] Attempt to overwrite/reinitialize detected!', newValue);
      console.log('Stack trace:\n', new Error().stack);
    }
  });
  console.log('✅ dataLayer monitoring active');
})();