chrome extension header listener

headerListener.js

// https://developer.chrome.com/extensions/declarativeWebRequest

chrome.declarativeWebRequest.onMessage.addListener(details => {
  console.log(details)
});

var rule1 = {
  conditions: [
    new chrome.declarativeWebRequest.RequestMatcher({
      // We at least should have the header being returned!
      excludeResponseHeaders : [{nameEquals: "X-Whatever"}]
    }),
    new chrome.declarativeWebRequest.RequestMatcher({
      excludeResponseHeaders : [{nameEquals: "X-Whatever", valueContains: ['f','a'] }]
    })
  ],
  actions: [
    new chrome.declarativeWebRequest.SendMessageToExtension({message : "issue detected"})
  ]
};

chrome.declarativeWebRequest.onRequest.addRules([rule1]);