How Ajax works

The core of AJAX is the JavaScript Object XMLHttpRequest. This object was first introduced in Internet Explorer 5. It is a technology that supports asynchronous requests. In short, XMLHttpRequest allows you to use JavaScript to request and process responses to the server without blocking users.

When creating a web site, executing screen updates on the client gives you great flexibility. The following functions can be completed using Ajax:

Dynamically update the total number of items in the shopping cart. You do not need to click Update and wait for the server to resend the entire page.

This improves site performance by reducing the amount of data downloaded from the server. For example, on a shopping cart page, when updating the number of items in the basket, the entire page is reloaded, which must download the data of the entire page. If Ajax is used to calculate the new total, the server returns only the new total value, so the required bandwidth is only 1% of the original total. This eliminates the page refresh for each user input. For example, in Ajax, if you click Next on the page list, the server data will only refresh the list rather than the whole page.
Directly edit table data, rather than requiring users to navigate to a new page to edit data. For Ajax, When you click Edit, You can refresh the static table as an editable table. After you Click Done, you can send an Ajax request to update the server and refresh the table so that it contains static and read-only data.

Everything is possible! Hopefully it will inspire you to start developing your own Ajax-based site. However, before getting started, let's introduce an existing web site that follows the traditional example of submitting, waiting, and re-displaying. We will also discuss how Ajax improves user experience.

The working principle of AJAX is equivalent to adding an intermediate layer between the user and the server, so that user operations and server responses are asynchronous. In this way, the previous server workload is transferred to the client, which facilitates the idle processing capability of the client to reduce the burden on the server and bandwidth, this saves ISP space and bandwidth rental costs.