@nightwatch/nightwatch-inspector/src/panel/js/index.js

Nightwatch Inspector that allows you to tests command directly from the browser

/* eslint-disable no-undef */

const tabID = chrome.devtools.inspectedWindow.tabId;

const backgroundPageConnection = chrome.runtime.connect({
  name: 'Nightwatch Inspector'
});

function sendMessageToBackground(action = null, content = null) {
  backgroundPageConnection.postMessage({
    tabId: chrome.devtools.inspectedWindow.tabId,
    action: action,
    content: content
  });
}

//Establishing connention with background.js
sendMessageToBackground('INIT');

backgroundPageConnection.onMessage.addListener(function (message) {
  // Handle responses from the background page, if any
});