Is ajax js?

ajax is not js. js, the full name of JavaScript, is a programming language; ajax is not a programming language, it is a technology based on javascript for creating fast dynamic web pages. It is a technology that can update part of the web page without reloading the entire web page. .

The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.

ajax is not js.

js stands for JavaScript, which is a programming language for the Web. It is a scripting language that belongs to the Internet. It is widely used in Web application development and is often used to add various dynamic functions to web pages. Provide users with a smoother and more beautiful browsing effect.

And ajax is not a programming language, it is a technology used to create better, faster and more interactive web applications.

Ajax is Asynchronous Javascript And XML (asynchronous JavaScript and XML).

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

ajax is a technology that can update parts of a web page without reloading the entire web page.

ajax is a technology used to create fast dynamic web pages. By exchanging small amounts of data with the server in the background. Ajax allows web pages to be updated asynchronously. This means that parts of a web page can be updated without reloading the entire page. If traditional web pages (which do not use ajax) need to update content, the entire web page must be reloaded.

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

Advantages and disadvantages of AJAX

1. Advantages of AJAX

1) No refresh update data.

The biggest advantage of AJAX is that it can communicate with the server to maintain data without refreshing the entire page. This allows web applications to respond to user interactions more quickly and avoids sending unchanged information over the network, reducing user waiting time and bringing a very good user experience.

2) Communicate with the server asynchronously.

AJAX uses an asynchronous method to communicate with the server, without interrupting the user's operation, and has a faster response capability. Optimizes the communication between Browser and Server, reducing unnecessary data transmission, time and data traffic on the network.

3) Front-end and back-end load balancing.

AJAX can transfer some of the work previously burdened by the server to the client, using the client's idle capabilities to process it, reducing the burden on the server and bandwidth, and saving space and broadband rental costs. And to reduce the burden on the server, the principle of AJAX is to "get data on demand", which can minimize the burden on the server caused by redundant requests and responses and improve site performance.

4) Widely supported based on standards.

AJAX is based on standardized and widely supported technology and does not require downloading browser plug-ins or applets, but requires the customer to allow JavaScript to execute on the browser. 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.

5) Separation of interface and application.

Ajax separates the interface and application in the WEB (which can also be said to separate data and presentation), which is conducive to division of labor and cooperation, reduces WEB application errors caused by non-technical personnel modifying the page, improves efficiency, and also More suitable for current publishing systems.

2. Disadvantages of AJAX

1) AJAX kills the Back and History functions, which is a destruction of the browser mechanism.

In the case of dynamically updated pages, users cannot return to the previous page state because the browser can only remember static pages in the history. The difference between a page that has been read completely and a page that has been dynamically modified is very subtle; users will often expect that clicking the back button will cancel their previous operation, but in an Ajax application, this will not be possible. .

The back button is an important function of a standard web site, but it cannot cooperate well with js. This is a serious problem caused by Ajax, because users often hope to cancel the previous operation by going back. So is there any solution to this problem? The answer is yes. Those who have used Gmail know that the Ajax technology used under Gmail solves this problem. You can go back under Gmail. However, it does not change the mechanism of Ajax. It is just a stupid but effective one. The way to do this is by creating or using 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 the Ajax element to restore the application state to what it was at that time.)

However, although this problem can be solved, the development cost it brings is very high, and is contrary to the rapid development required by the Ajax framework. This is a very serious problem caused by Ajax.

A related point is that using dynamic page updates makes it difficult for users to save a specific state to favorites. Solutions to this problem have also emerged, most of which use URL fragment identifiers (often called anchors, the part after the # in the URL) to keep track of and allow the user to return to a specified application state. (Many browsers allow JavaScript to dynamically update anchors, allowing Ajax applications to update anchors while updating the displayed content.) These solutions also resolve many of the arguments surrounding not supporting a back button.

2) AJAX security issues.

AJAX technology not only brings a good user experience to users, but also brings new security threats to IT companies. Ajax technology is like establishing a direct channel for enterprise data. This allows developers to inadvertently expose more data and server logic than before. Ajax logic can be hidden from client-side security scanning technologies, allowing hackers to create new attacks from remote servers. Ajax is also difficult to avoid some known security weaknesses, such as cross-site scripting attacks, SQL injection attacks, and Credentials-based security vulnerabilities, etc.

3) Weak support for search engines.

The support for search engines is relatively weak. If used improperly, AJAX will increase network data traffic, thereby reducing the performance of the entire system.

4) Destroy the exception handling mechanism of the program.

At least from the current perspective, Ajax frameworks such as Ajax.dll and Ajaxpro.dll will destroy the exception mechanism of the program. Regarding this problem, I have encountered it during the development process, but after checking, there is almost no relevant introduction on the Internet. Later, we did an experiment and used Ajax and traditional form submission modes to delete a piece of data... which brought great difficulties to our debugging.

5) Violates the original intention of URL and resource positioning.

For example, if I give you a URL address, if Ajax technology is used, maybe what you see under the URL address is different from what I see under this URL address. This is contrary to the original intention of resource positioning.

6) AJAX does not support mobile devices well.

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

7) The client is too fat, and too much client code causes development costs.

The writing is complex and error-prone; there are many redundant codes (it is a common problem of AJAX to include js files in layers, plus a lot of server-side code in the past is now placed on the client); it destroys the original features of the Web standard.

[Related tutorial recommendations: AJAX video tutorial]

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