requestInterceptor.js

// requestInterceptor.js

const hostnameWhitelist = ['api.example.com', 'another.api.com'];

// Original functions
const originalFetch = window.fetch;
const originalXMLHttpRequest = window.XMLHttpRequest;
const originalSendBeacon = navigator.sendBeacon.bind(navigator);
const originalWebSocket = window.WebSocket;

function isUrlAllowed(url) {
  const parsedUrl = new URL(url, window.location.href);
  return hostnameWhitelist.includes(parsedUrl.hostname);
}

// Override fetch
window.fetch = async (...args) => {
  if (isUrlAllowed(args[0])) {
    return originalFetch(...args);
  } else {
    throw new Error("Fetch request blocked by interceptor.");
  }
};

// Override XMLHttpRequest
window.XMLHttpRequest = function() {
  const xhr = new originalXMLHttpRequest();
  const originalOpen = xhr.open;
  xhr.open = function(method, url, ...args) {
    if (isUrlAllowed(url)) {
      originalOpen.call(xhr, method, url, ...args);
    } else {
      console.error("XMLHttpRequest blocked by interceptor.");
      // Throwing an error might be too disruptive; consider alternatives
    }
  };
  return xhr;
};

// Override sendBeacon
navigator.sendBeacon = (url, data) => {
  if (isUrlAllowed(url)) {
    return originalSendBeacon(url, data);
  } else {
    console.error("sendBeacon request blocked by interceptor.");
    return false; // sendBeacon returns a boolean indicating success/failure
  }
};

// Override WebSocket
window.WebSocket = function(url, protocols) {
  if (isUrlAllowed(url)) {
    return new originalWebSocket(url, protocols);
  } else {
    console.error("WebSocket connection blocked by interceptor.");
    // Consider throwing an error or returning a dummy object depending on how you want to handle blocked attempts
    throw new Error("WebSocket connection blocked by interceptor.");
  }
};