chrome-extensions-samples/functional-samples/tutorial.open-api-reference/sw-tips.js

console.log('sw-tips.js');

// Fetch tip & save in storage
const updateTip = async () => {
  const response = await fetch('https://extension-tips.glitch.me/tips.json');
  const tips = await response.json();
  const randomIndex = Math.floor(Math.random() * tips.length);
  await chrome.storage.local.set({ tip: tips[randomIndex] });
};

// Create a daily alarm and retrieves the first tip when extension is installed.
chrome.runtime.onInstalled.addListener(({ reason }) => {
  if (reason === 'install') {
    chrome.alarms.create({ delayInMinutes: 1, periodInMinutes: 1440 });
    updateTip();
  }
});

// Retrieve tip of the day
chrome.alarms.onAlarm.addListener(updateTip);

// Send tip to content script via messaging
chrome.runtime.onMessage.addListener((message, sender, sendResponse) => {
  if (message.greeting === 'tip') {
    chrome.storage.local.get('tip').then(sendResponse);
    return true;
  }
});