When can you confirm that SessionStorage has been deleted?

How to determine when SessionStorage has been deleted?

Introduction:
SessionStorage is a client-side storage method provided in HTML5 for saving data during a browser session. Compared with cookies, the data stored in SessionStorage will not be sent to the server and will not be lost when the page is refreshed. However, sometimes we need to clear the data in SessionStorage to free up storage space or reset user state. This article explains how to determine when SessionStorage has been deleted and provides specific code examples.

1. Determine whether SessionStorage has been deleted:

Using SessionStorage, we can continuously store and access data during the browser session. However, when the browser session ends, the data in SessionStorage is deleted. In order to determine whether the SessionStorage has been deleted, we can determine by checking the length of the SessionStorage. When there is no data in SessionStorage, its length is 0, indicating that the data has been deleted.

The following is a code example to determine whether SessionStorage has been deleted:

if (sessionStorage.length === 0) {
  console.log('SessionStorage has been deleted.');
} else {
  console.log('SessionStorage still exists.');
}

2. Clear the data in SessionStorage:

If we want to clear SessionStorage For data in, we can use the sessionStorage.clear() method. This method will delete all data in SessionStorage, returning it to its original state.

The following is a code example for clearing data in SessionStorage:

sessionStorage.clear();
console.log('SessionStorage has been cleared.');

3. Set SessionStorage expiration time:

If we want SessionStorage to expire at a certain Automatically delete after time, we can use timer to achieve this. By calling the sessionStorage.clear() method after a specific interval, we can achieve automatic clearing of SessionStorage data.

The following is a code example for setting the SessionStorage expiration time and automatically deleting data:

const expirationTime = 60 * 60 * 1000; // 过期时间为 1 小时

setTimeout(() => {
  sessionStorage.clear();
  console.log('SessionStorage has expired and been cleared.');
}, expirationTime);

In the above code, we set the expiration time to 1 hour (60 minutes). When 1 hour has passed, the timer will trigger and call the sessionStorage.clear() method to clear the data in SessionStorage.

Summary:
Determining whether SessionStorage has been deleted can be judged by checking whether its length is 0. To clear the data in SessionStorage, we can use the sessionStorage.clear() method. If you want SessionStorage to be automatically deleted after a certain period of time, we can use a timer to achieve this.

Please note that in some cases, such as the user manually closing the browser or clearing the browser cache, the data in SessionStorage will also be deleted. Therefore, when designing your application, be sure to take these situations into account and prepare for possible data loss.

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