XMLHttpRequest

XMLHttpRequest is an API in JavaScript that provides client functionality for transferring data between a client and a server. It allows web pages to make HTTP requeststo web servers, which is essential for retrieving or submitting data without having to reload the entire page.

This API is a key component in Ajax (Asynchronous JavaScript and XML) programming.

It can send requests to the server asynchronously, meaning the page doesn't need to be reloaded for the entire web page to update. It can be used to transfer various types of data, including text, XML, JSON, and binary data (like images and videos).

XMLHttpRequest supports several HTTP methods, such as GET, POST, PUT, DELETE, etc., allowing for a wide range of operations like fetching data, submitting forms, and updating or deleting resources.

The response from a server can be processed in various formats, such as text, XML, or JSON. The API provides ways to handle these responses and update the web page accordingly.

You can set custom HTTP headers and send credentials (like cookies or authentication data) with requests.