Set an Expiration Date and Time for a localStorage Item

OpenJavaScript 0

Last updated: January 20, 2023.

Unlike cookies, localStorage has no native option for setting an expiration time to an item.

But you can mimic this behavior with localStorage by adding a expiration timestamp when storing an item:

const obj = { value: "value", expires: new Date().setDate(new Date().getDate() + 30).toString() };
// Saves timestamp for 30 days in the future

localStorage.setItem('test-expiration', JSON.stringify(obj));
// Stores obj as string in localStorage

Then, you check the timestamp you have saved when a user visits your site.

If the value of the expiration timestamp is greater than the timestamp for now, the set expiration time has passed and the item should be deleted:

const res = new Date().getTime().toString() > JSON.parse(localStorage.getItem('test-expiration')).expires;
// Returns true if timestamp for now is greater than expiration (item has 'expired')

if (res) {
  // item is removed if the value of res is true

If you want an item in storage to only persist for a current session, use the sessionStorage method.

It works in exactly the same way as localStorage except all items are automatically cleared once a user closes the current tab:

sessionStorage.setItem('test', 'value');
// Stores test item in sessionStorage space

Run this code and then close the current tab.

When you return the item will not longer exist:

sessionStorage.getItem('test' === null);
// true