const {name} = browser.runtime.getManifest(); console.log(name, "background page loaded"); browser.runtime.onMessage.addListener((msg, sender, sendResponse) => { console.log(name, "background received msg", {msg, sender}); switch (msg) { case "test - sendMessage with returned Promise reply": try { browser.pageAction.show(sender.tab.id); } catch (err) { return Promise.resolve(`Unexpected error on pageAction.show: ${err}`); } return Promise.resolve("bg page reply 1"); case "test - sendMessage with returned value reply": // This is supposed to be ignored and the sender should receive // a reply from the second listener. return "Unexpected behavior: a plain return value should not be sent as a result"; case "test - sendMessage with synchronous sendResponse": sendResponse("bg page reply 3"); return "value returned after calling sendResponse synchrously"; case "test - sendMessage with asynchronous sendResponse": setTimeout(() => sendResponse("bg page reply 4"), 50); return true; case "test - second listener if the first does not reply": // This is supposed to be ignored and the sender should receive // a reply from the second listener. return false; case "test - sendMessage with returned rejected Promise with Error value": return Promise.reject(new Error("rejected-error-value")); case "test - sendMessage with returned rejected Promise with non-Error value": return Promise.reject("rejected-non-error-value"); case "test - sendMessage with returned rejected Promise with non-Error value with message property": return Promise.reject({message: "rejected-non-error-message"}); case "test - sendMessage with listener callback throws": throw new Error("listener throws"); case "test - sendMessage and no listener answers": return undefined; default: return Promise.resolve( `Unxpected message received by the background page: ${JSON.stringify(msg)}\n`); } }); browser.runtime.onMessage.addListener((msg, sender, sendResponse) => { if (msg === "test - sendMessage and no listener answers") { return undefined; } setTimeout(() => { sendResponse("second listener reply"); }, 100); return true; }); console.log(name, "background page ready to receive a content script message...");