chrome-extensionListen for a message in background script

chrome.runtime.onMessage.addListener(
  function(req, sender, cb) {
    console.log(req);
    cb({other: 'value'});
  }
);ctrl + cyoutubegithub

`onMessage.addListener` listens to a message	`console.log(req);` code to process request `req` object, passed while sending a message
`cb({other: 'value'})` send response to message sender with any object as an argument