Under what circumstances will SessionStorage be cleared?

SessionStorage is a technology provided by HTML5 for storing data in the browser. It is similar to LocalStorage, but has some specific usage scenarios and limitations. This article will introduce under what circumstances SessionStorage will be deleted and provide specific code examples.

SessionStorage is a session-level storage mechanism. Its data is only valid in the current session (that is, the current browser window or tab) and is automatically cleared after the session ends. Specifically, the following situations will cause SessionStorage to be deleted:

1. Close the browser window or tab
   When the user closes the browser window or tab, the session will end. The data saved in SessionStorage will be deleted. This is because SessionStorage is associated with the session and is only valid in the current session.

2. Manually clear SessionStorage
   Developers can manually clear all data saved in SessionStorage by calling the clear() method of SessionStorage. For example:

   sessionStorage.clear();

3. The browser crashes or exits abnormally
   If the browser crashes or exits abnormally, the data in SessionStorage will be lost. This is because the data in the session is stored in the browser's memory rather than persisted to the hard disk.

The following is a code example that demonstrates how to use SessionStorage to store and read data:

// 存储数据
sessionStorage.setItem('name', 'Tom');
sessionStorage.setItem('age', '25');

// 读取数据
var name = sessionStorage.getItem('name');
var age = sessionStorage.getItem('age');

console.log(name); // 输出：Tom
console.log(age);  // 输出：25

It should be noted that only string type data can be stored in SessionStorage. If you want to store other types of data, you need to use the JSON.stringify() method to convert it to a string before storing it. When reading data, you can use the JSON.parse() method to convert the string into the original data type.

In short, SessionStorage is a temporary storage mechanism suitable for scenarios where data needs to be maintained during the session. But you need to remember that its data has a certain timeliness and will be automatically deleted under certain circumstances. When using SessionStorage, pay attention to the data storage timing and life cycle to avoid data loss or inconsistency.

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