What is the function of localStorage in web development?

The function of localStorage in web development is to store data persistently in a user's browser per origin. This means that data saved in localStorage will be available even after the browser is closed and reopened, unlike sessionStorage, which is cleared when the session ends (i.e., when the tab or window is closed).

localStorage enables web applications to save key-value pairs in a web browser. The data persists across page reloads and browser sessions, allowing for the retention of user preferences, settings, or any information that should be maintained for future visits. The data remains intact until it is explicitly deleted by the application or the user, making it ideal for storing user-specific information that enhances user experience without requiring constant retrieval from a server.

This functionality is key in web development as it allows applications to maintain state, improve performance by minimizing server requests for string data, and enhance the overall user experience by providing a more personalized interaction with the application.