Ajax advantages and disadvantages

Advantages of AJAX

The benefits brought to us by Ajax are basically profound experiences. Here I will only briefly talk about the following points: 1. The biggest point is that the page is refreshed and communicates with the server on the page, the user experience is very good. 2. Use asynchronous mode to communicate with the server, without interrupting user operations, so as to have a more rapid response capability. 3. Some of the previous server workload can be transferred to the client, and the client's idle capabilities can be used to handle the workload, reduce the load on servers and bandwidth, and save space and bandwidth rental costs. In addition, it reduces the burden on the server. The Ajax principle is to "retrieve data on demand", which can minimize the burden on the server caused by redundant requests and responses. 4. Based on standardized and widely supported technologies, you do not need to download plug-ins or applets. The disadvantages of Ajax: I will focus on the defects of Ajax, because most of the problems we usually pay attention to are the benefits brought to us by Ajax, such as the improvement of user experience. The defects caused by Ajax are ignored. The Ajax defects described below are inherent in nature. 1. Ajax kills the back button, which destroys the browser's back-up mechanism. The back button is an important feature of a standard web site, but it cannot cooperate well with Js. This is a serious problem caused by Ajax, because users often want to cancel the previous operation by going back. Is there any way to solve this problem? The answer is yes. If you have used Gmail, the Ajax technology used in Gmail solves this problem. You can withdraw from Gmail. However, it cannot change the Ajax mechanism either. It is just a stupid but effective method, that is, when the user clicks the back button to access the history, create or use a hidden IFRAME to reproduce changes on the page. (For example, when a user clicks back in Google Maps, it searches in a hidden IFRAME and then reflects the search result to the Ajax element, to restore the application status to the current state .) However, although this problem can be solved, it brings about a very high development cost, which is different from the rapid development required by the Ajax framework. This is a very serious problem caused by Ajax. 2. Security Technology 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 before. The Ajax logic can be hidden from the client's security scanning technology, allowing hackers to create new attacks from remote servers. There are also known security vulnerabilities that cannot be avoided by Ajax, such as cross-site scripting attacks, SQL injection attacks, and credentials-based security vulnerabilities. 3. weak support for search engines. 4. destroys the abnormal mechanism of the program. At least from the current perspective, Ajax frameworks such as Ajax. dll and ajaxpro. dll will destroy the program's exception mechanism. I have encountered this problem during the development process, but I have found that there is almost no relevant introduction on the Internet. Later, I did a test to delete a piece of data in Ajax and traditional form submission modes ...... It brings great difficulties to our debugging. 5. In addition, some other problems, such as violating the original intention of URL and resource positioning. For example, if Ajax technology is used, what you see under the URL address is different from what I see under the URL address. This is contrary to the original intention of resource positioning. 6. Some handheld devices (such as mobile phones and PDAs) cannot support Ajax yet. For example, when we open a website using Ajax technology on a mobile browser, it is currently not supported. Of course, this problem has nothing to do with us.

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