function tootInfo(message) { tootContent = message.artist + " - " + message.title url = "http://localhost:5000/toot?content=" + tootContent fetch(url) .then(function (response) { return response; }) .then(function (response) { console.log("Got response : " + response); }) .catch(function (error) { console.log("Error while tooting: " + error); }) } function handleResponse() { document.getElementById("artist").innerText = message.artist document.getElementById("title").innerText = message.title } function handleError(error) { console.log(`Error: ${error}`); } function getCurrentInfo () { var gettingActiveTab = browser.tabs.query({active: true, currentWindow: true}) gettingActiveTab.then((tabs) => { browser.tabs.sendMessage(tabs[0].id, {command: "get-info"}) .then(handleResponse, handleError); }) } button = document.getElementById('toot-button') browser.browserAction.onClicked.addListener(getCurrentInfo) button.onclick = tootInfo browser.tabs.executeScript(null, { file: "/content_script.js" });