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This article mainly introduces ajax is not js, the article is very detailed, has a certain reference value, interested friends must read!

Ajax is not JS. JS full name JavaScript, is a programming language; Ajax is not a programming language, is based on javascript for the creation of a fast dynamic web page technology, is a need to reload the entire web page, able to update part of the web page technology.

Operating environment of this tutorial: Windows 7 system, Javascript version 1.8.5, Dell G3 computer.

Ajax is not JS.

JS full name JavaScript, is a Web-oriented programming language, is a kind of network script language, is widely used in Web application development, often used to add a variety of dynamic functions for web pages, to provide users with a more smooth and beautiful browsing effect.

Ajax is not a programming language, but a technology for creating better, faster, and more interactive Web applications.

Ajax stands for Asynchronous JavaScript And XML.

Ajax is the art of exchanging data with a server and updating parts of a web page without reloading the entire page.

Ajax is a technology that allows you to update parts of a web page without having to reload the entire page.

Ajax is a technology for creating fast and dynamic web pages. By exchanging small amounts of data with servers in the background. Ajax enables asynchronous updating of web pages. This means that you can update parts of a web page without reloading the entire page. Traditional web pages (which do not use ajax) must reload the entire web page if they need to update content.

Ajax applications use web browsers that support the above technologies as platforms. These browsers currently include Mozilla, Firefox, Internet Explorer, Opera, Konqueror and Safari. Opera, however, does not support XSL format objects, nor does it support XSLT.

Advantages of AJAX

1. Advantages of Ajax

1) No update data.

The biggest advantage of AJAX is the ability to communicate with the server to maintain data without refreshing the entire page. This allows Web applications to respond more quickly to user interactions and avoids sending unchanged information over the network, reducing user wait times and resulting in a very good user experience.

2) Asynchronous communication with the server.

AJAX uses asynchronous communication with the server without interrupting the user's operations and has a faster response capability. Optimize communication between Browser and Server, reduce unnecessary data transmission, time and reduce data traffic on the network.

3) Front and back end load balancing.

AJAX can shift some of the work previously burdened by servers to the client, taking advantage of the client's idle capacity to process, reducing the burden on servers and bandwidth, saving space and broadband rental costs. And reduce the burden on the server, AJAX principle is "data on demand," can minimize the burden of redundant requests and responses to the server, improve site performance.

4) Standards are widely supported.

AJAX is based on standardized and widely supported technology that does not require downloading browser plug-ins or Mini programs, but requires the client to allow JavaScript to execute on the browser. As Ajax matures, libraries that simplify how Ajax is used appear. Similarly, another programming aid technique has emerged to provide alternative functionality for users who do not support JavaScript.

5) Interface and application separation.

Ajax separates the interface and application in WEB (it can also be said that the data is separated from the presentation), which is conducive to division of labor and cooperation, reduces the WEB application errors caused by the modification of pages by non-technical personnel, improves efficiency, and is more suitable for the current publishing system.

Disadvantages of AJAX

1) AJAX kills the Back and History functions, i.e., breaks the browser mechanism.

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 difference between a fully loaded page and one that has been modified dynamically is subtle; users usually want to click the Back button to cancel their previous action, but in Ajax applications, this is not possible.

The back button is an important feature of a standard web site, but it doesn't work well with js. This is a serious problem with Ajax because users often want to be able to undo a previous action by going backwards. So is there a way around this? The Ajax technology used under Gmail solves this problem. It can be reversed under Gmail, but it doesn't change the Ajax mechanism. It just uses a stupid but effective way to reproduce changes on the page by creating or using a hidden IFRAME when the user clicks the Back button to access the history. (For example, when a user clicks back in Google Maps, it searches in a hidden IFRAME and then reflects the search results onto Ajax elements to restore the application state to that state.)

However, while this problem is solvable, the development costs it imposes are very high and run counter to the rapid development required by the Ajax framework. This is a very serious problem with Ajax.

A related point is that using dynamic page updates makes it difficult for users to save a particular state to favorites. Solutions to this problem have also emerged, mostly using URL fragment identifiers (often called anchor points, the part of the URL that follows the #) to keep track, allowing users to return to a specified application state. (Many browsers allow JavaScript to update anchors dynamically, which enables Ajax applications to update anchors as they update their display content.) These solutions also resolve many of the arguments about not supporting the Back button.

2) AJAX security issues.

AJAX technology brings users a good user experience, but it also brings new security threats to IT enterprises. Ajax technology is like establishing a direct channel for enterprise data. This allows developers to inadvertently expose more data and server logic than ever before. Ajax logic can be hidden from client-side security scanning techniques, allowing hackers to establish new attacks from remote servers. Ajax is also vulnerable to known security vulnerabilities, such as cross-site footstep attacks, SQL injection attacks, and Credentials based vulnerabilities.

3) Weak support for search engines.

Support for search engines is weak. If used incorrectly, AJAX can increase network data traffic, which can reduce overall system performance.

4) Destroy the exception handling mechanism of the program.

Ajax frameworks like Ajax.dll and Ajaxpro.dll are, at least for now, the ones that break the exception mechanism of your program. About this problem, I have encountered it in the development process, but there is almost no relevant introduction on the Internet. Later, we did an experiment to delete a piece of data using Ajax and traditional form submission patterns respectively... which brought great difficulties to our debugging.

5) Contrary to the original intention of URL and resource positioning.

For example, if I give you a URL and Ajax is used, maybe what you see at that URL is different from what I see at that URL. This is contrary to the original intention of resource positioning.

6) AJAX does not support mobile devices very well.

Some handheld devices (such as mobile phones, PDAs, etc.) do not support Ajax very well, for example, when we open a website using Ajax technology on the browser of a mobile phone, it is currently not supported.

7) Client fat, too much client code causes development costs.

Complicated and error-prone; redundant code (layers containing js files are common to AJAX, plus a lot of previous server-side code is now placed on the client); destroying the original standards of the Web.

The above is "Ajax is not JS" all the content of this article, thank you for reading! Hope to share the content to help everyone, more relevant knowledge, welcome to pay attention to the industry information channel!

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