pup-local.js

const restoreLocalStorage = async () => {
    let json = JSON.parse(fs.readFileSync(`${__dirname}/local.json`));
    await page.evaluate(json => {
      localStorage.clear();
      for (let key in json)
        localStorage.setItem(key, json[key]);
    }, json);
  }

  const saveLocalStorage = async () => {
    console.log("saving");
    const json = await page.evaluate(() => {
      let json = {};
      for (let i = 0; i < localStorage.length; i++) {
        const key = localStorage.key(i);
        json[key] = localStorage.getItem(key);
      }
      return json;
    });
    console.log(json);
    fs.writeFileSync(`${__dirname}/local.json`, JSON.stringify(json));