What is Ajax used for?

What is Ajax used for?

Ajax refers to a web development technology that creates interactive, fast and dynamic web applications. It can update part of the web page without reloading the entire web page, and can communicate with the server in the background. By exchanging a small amount of data, web pages can be updated asynchronously.

Ajax has disadvantages

The biggest advantage of using Ajax is that it can maintain data without updating the entire page. This allows web applications to respond more quickly to user actions and avoids sending unchanged information over the network.

Ajax does not require any browser plug-ins, but requires the user to allow JavaScript to execute on the browser. Just like DHTML applications, Ajax applications must be rigorously tested on many different browsers and platforms. As Ajax matures, some program libraries that simplify the use of Ajax have also come out. Likewise, another assistive programming technology has emerged to provide alternative functionality for users who do not support JavaScript.

The main criticism of using Ajax is that it can break the browser's back and bookmark functionality. In the case of dynamically updated pages, the user cannot go back to the previous page state because the browser can only remember static pages in the history. The possible differences between a page that has been completely read and a page that has been dynamically modified are very subtle; users often expect to click the back button to cancel their previous operation, but in an Ajax application, this is not the case. Unable to do so. However, developers have come up with various ways to solve this problem. Most of the methods before HTML5 were to create or use a hidden IFRAME to reproduce the changes on the page when the user clicks the back button to access the history. (For example, when the user clicks back in Google Maps, it searches in a hidden IFRAME and then reflects the search results onto an Ajax element to restore the application state to what it was at that time).

Regarding the problem of not being able to add status to favorites or bookmarks, one way before HTML5 was to use URL fragment identifiers (often called anchors, the part after the # in the URL) to keep track of, allowing The user returns to a specified application state. (Many browsers allow JavaScript to dynamically update anchors, which allows Ajax applications to update anchors while updating the displayed content.) HTML5 will later be able to directly manipulate browsing history, store web page status in the form of strings, and add web pages to web favorites. When clipping or bookmarking, the state is retained invisibly. The above two methods can also solve the problem of being unable to retreat at the same time.

When developing Ajax, network latency—that is, the interval between the user's request and the server's response—needs to be carefully considered. Not giving users a clear response, not properly pre-reading data, or improperly handling XMLHttpRequest will make users feel bored. A common solution is to use a visual component to tell the user that the system is performing background operations and reading data and content.

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