Updating display of elements on the web page without refreshing the whole page

Question

Last time I coded a web application was almost 10 years ago. I used Java/JSP/HTML/CSS etc. I've been coding non-web applications only ever since.

When I look at modern sites now (like this one), I realize how my web development skills are obsolete. Maybe the most obvious "feature" that I wouldn't know how to implement now is the update of elements on the page after user input without having to refresh the whole page (e.g. the voting/downvoting here updates the vote count without reloading the whole page). What are the basic technologies behind this?

Answer 1

The techniques come under the umbrella of AJAX:

Ajax (shorthand for asynchronous JavaScript and XML) is a group of interrelated web development techniques used on the client-side to create interactive web applications. With Ajax, web applications can retrieve data from the server asynchronously in the background without interfering with the display and behavior of the existing page. The use of Ajax techniques has led to an increase in interactive or dynamic interfaces on web pages. Data is usually retrieved using the XMLHttpRequest object. Despite the name, the use of XML is not actually required, nor do the requests need to be asynchronous.

Answer 2

Something you should know:

1. DHTML : HTML Document structure,document event;
2. JAVASCRIPT: use javascript to operate the HTML document;
3. AJAX: use javascript to communicate with the server.