In front-end development, it is often necessary to store and manage data on the browser side. In order to achieve persistent storage and convenient access to data, JavaScript provides a variety of data storage methods. This article will introduce several common front-end JS data storage methods and their characteristics.
1. Cookie
A cookie is a small text file that is stored on the user's computer by the browser. Cookies can be read and written using JavaScript. Cookies are mainly used to store a small amount of data and are automatically sent to the server in each HTTP request. However, the storage capacity of cookies is limited, usually no more than 4KB, and is limited by browser settings.
2. LocalStorage
LocalStorage is a persistent local storage mechanism introduced by HTML5. It allows large amounts of data to be stored in the browser and persist even after the browser is closed. LocalStorage uses simple key-value pairs to store data, which can be accessed and manipulated through JavaScript's localStorage object. The storage capacity of LocalStorage is usually 5MB or more, but since it stores data on the user's browser, care should be taken not to store sensitive or important information.
3. SessionStorage
SessionStorage is similar to LocalStorage and is also a local storage mechanism provided by HTML5. The difference is that the data stored in SessionStorage will be cleared after the browser session ends, instead of persistent storage. SessionStorage is suitable for temporarily saving session data, such as sharing data between the same browser tab or window.
4. IndexedDB
IndexedDB is an advanced client-side database for storing structured data in the browser. It provides a transactional storage mechanism and rich query functions. IndexedDB is suitable for scenarios that need to store a large amount of structured data or perform complex queries. Compared with other storage methods, IndexedDB has a steep learning curve and needs to use JavaScript API to operate.
5. Web Storage API
Web Storage API is a unified API, including LocalStorage and SessionStorage. It provides a set of simple interfaces for accessing and manipulating these two storage methods. Data can be easily read, written, and deleted through the Web Storage API.
6. Other storage methods
In addition to the storage methods mentioned above, there are some other storage methods to choose from, such as WebSQL, FileSystem API, etc. However, due to issues such as compatibility and usage limitations of these storage methods, their use has gradually declined and they are no longer widely recommended.
Summarize
Developers can choose the appropriate storage method according to specific needs. Cookies are suitable for storing small data and session-related information, LocalStorage and SessionStorage are suitable for persistent or temporary storage in the browser, and IndexedDB is suitable for processing large amounts of structured data and complex queries. Using these data storage methods, front-end data can be effectively managed and utilized.
If you want to see what data is stored on the current website, you can click "F12" and switch to the "Storage" tab in the developer tools. Among them,
session storage is SessionStorage; local storage is localStorage
