HTML Web Storage API is a way to store key-value pairs in the user’s web browser. It provides two objects, localStorage and sessionStorage, that allow you to store and access data locally on the user’s computer.

The localStorage object stores data without an expiration date. The data will not be deleted when the browser is closed, and will be available even after the computer is restarted. This makes it a good option for storing long-term data, such as user preferences.

The sessionStorage object stores data for a single session. The data will be deleted when the browser is closed or the user navigates away from the page. This makes it a good option for storing data that is only needed for a short period of time, such as form data.

Both localStorage and sessionStorage use the same API for storing and retrieving data. To store data, you use the setItem() method, which takes two arguments: a key and a value. The key is a string that identifies the data, and the value can be any data type that can be serialized as a string. For example, to store a user’s name in localStorage, you could use the following code:

localStorage.setItem('name', 'John Doe');

To retrieve the data, you use the getItem() method, which takes the key as an argument and returns the value. For example, to retrieve the user’s name from localStorage, you could use the following code:

var name = localStorage.getItem('name');

You can also remove data from localStorage or sessionStorage using the removeItem() method, which takes the key as an argument:

localStorage.removeItem('name');

The HTML Web Storage API also provides an event called storage, which is fired when a change is made to the localStorage or sessionStorage object. This allows you to synchronize data between multiple windows or tabs of the same website.

Overall, the HTML Web Storage API provides a convenient way to store and retrieve data in the user’s web browser, making it a useful tool for creating web applications that require local data storage.

The sessionStorage object is a part of the HTML Web Storage API that allows web developers to store key-value pairs in the user’s browser for the duration of their browsing session. This means that data stored in sessionStorage is only available for the current browser session and is cleared when the browser is closed.

The syntax for storing data in sessionStorage is as follows:

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sessionStorage.setItem('key', 'value');

This sets a key-value pair in the sessionStorage object.

To retrieve data from sessionStorage, you can use the getItem() method, like so:

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sessionStorage.getItem('key');

You can also remove an item from sessionStorage using the removeItem() method:

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sessionStorage.removeItem('key');

sessionStorage has a few advantages over using cookies to store data. First, the data stored in sessionStorage is not sent to the server with every HTTP request, reducing the amount of data sent over the network. Second, sessionStorage allows for larger data storage (up to 5-10 MB, depending on the browser), whereas cookies are limited to 4KB. Finally, because the data stored in sessionStorage is only available for the duration of the browsing session, it can be a more secure option for sensitive data.

One important thing to note about sessionStorage is that it is only available within the same window or tab that created it. If you open a new window or tab, the sessionStorage object will be empty.

In summary, sessionStorage is a powerful tool for web developers to store data in the user’s browser for the duration of their browsing session. It offers advantages over cookies in terms of data storage and security, and its simple syntax makes it easy to use in your web applications.