farskid / localstorage-watcher Goto Github PK

window.localStorage.clear()

function getEntries(obj) {
  return Object.entries(obj);
}

const toHashMap = entries => entries.reduce((t, c) => {
  return {
    ...t,
    [c[0]]: c[1]
  }
}, {});

const hash = obj => encode(JSON.stringify(obj))

const encode = btoa;
const decode = atob;

function storageWatcher(duration = 1000, onChange = () => {}) {
  let lastHash = hash(window.localStorage),
    id;

  const hasChanged = () => hash(window.localStorage) !== lastHash;


  const check = () => {
    if (hasChanged()) {
      const entries = getEntries(window.localStorage);
      const hashMap = toHashMap(entries)
      lastHash = hash(window.localStorage);
      onChange(hashMap)
    }
  }

  return {
    start() {
      console.log('started')
      id = setInterval(check, duration);
    },
    stop() {
      console.log('stopped')
      clearInterval(id);
    }
  }
}


let w = storageWatcher(1000, storage => {
  console.log(`local storage changed`, storage)
});

w.start()



window.localStorage.setItem('a', 1);

setTimeout(() => window.localStorage.setItem('b', 2), 500);

setTimeout(() => window.localStorage.setItem('c', 3), 1500);

setTimeout(() => window.localStorage.removeItem('b'), 2500);

setTimeout(() => {
  window.localStorage.removeItem('a')
  window.localStorage.removeItem('c')

  window.localStorage.setItem('c', 3)
  window.localStorage.setItem('a', 1);

}, 1500);