Cache problem:
What is a cache problem? That is, when the input content of the browser is the same, that is, the requested URL is the same, the browser will read the cache. If the content is the same twice, it will not interact with the server.
Solution: Add a timestamp to the requested URL.
Through my test, IE and 360 will not interact with the server when the user name is entered twice. Firefox will still interact with the server even if the user name is entered the same twice.
That is: the temp value returned by the server in Firefox will increase by 1 each time, but IE and 360 will not change. Therefore, adding a timestamp will no longer cause caching problems in these three browsers.
Modified code:
AJAXServer.java
Caching problem
//The input content of the test code added to the caching problem remains unchanged in IE and the number of 360 times does not increase, but firefox will increase
Integer inte= (Integer) request.getSession().getAttribute("total");
int temp=0;
if(inte==null){
temp=1;
}else{
temp=inte.intValue() 1;
}
request.getSession().setAttribute("total",temp);
Add the above code to AJAXServer.java, and add the temp variable during out.println and return it to the client.
In this way, if the client's temp value is added, it means that the client and server interact, otherwise there is no interaction.
verify.js
//Add timestamp to url address, fool the browser and not read cache
function convertURL(url){
//Get timestamp
var timestamp=(new Date().valueOf());
//Splice the timestamp information into the url
//url="AJAXServer"
if(url.indexOf("? ")>=0){
url=url "&t=" timestamp;
}else{
url=url "?t=" timestamp;
}
return url;
}
function verifyCache(){
var url="AJAXServer?name=" $("#username").val();
url=convertURL(url); //Cache
$.get(url,null,function(data){
$("#result").html(data);
});
}
Due to I just asked about verification and caching issues. In order to facilitate the explanation of the problem, the verification method used is jquery encapsulated ajax to receive server-side text data.
》》》Similarly, don’t forget to modify the method called in ajax.html and change the name to verifyCache() in the above script
Chinese problem:
There are two solutions:
First Type: Use encodeURI once on the page side, and use String name=new String(old.getBytes("iso8859-1"),"UTF-8") on the server side;
Chinese 1
function verifychinese1{
var url="AJAXServer?name=" encodeURI($("#username ").val());
url=convertURL(url); //Cache
$.get(url,null,function(data){
$("#result").html( data);
});
》》》Add the above method to verify.js, and also add
String name=new String(old.getBytes("iso8859-1"),"UTF-8 ");
is added to the appropriate location in the AJAXServer.java class. For example, just put it after the PrintWriter code.
Similarly, when using the first method, don’t forget to modify the method called in ajax.html, and change the name to verifychinese1() in the above script.
Second method: Use encodeURI twice on the page side and on the server side. Use String name= URLDecoder.decode(old,"UTF-8");
Chinese 2
function verifychinese2(){
var url="AJAXServer?name=" encodeURI(encodeURI($("#username").val()));
url= convertURL(url); //Cache
$.get(url,null,function(data){
$("#result").html(data);
});
}
》》》Add the above method to verify.js, and add
String name= URLDecoder.decode(old, "UTF-8");
to AJAXServer.java the appropriate location in the class. For example, just put it after the PrintWriter code.
Similarly, when using the second method, don’t forget to modify the method called in ajax.html, and change the name to verifychinese2() in the above script.
If you need the source code, you can leave a message.
After a few days of study, I have a basic understanding of the dynamic verification of ajax. I will add corresponding content according to the situation in the future.

JavaScript is widely used in websites, mobile applications, desktop applications and server-side programming. 1) In website development, JavaScript operates DOM together with HTML and CSS to achieve dynamic effects and supports frameworks such as jQuery and React. 2) Through ReactNative and Ionic, JavaScript is used to develop cross-platform mobile applications. 3) The Electron framework enables JavaScript to build desktop applications. 4) Node.js allows JavaScript to run on the server side and supports high concurrent requests.

Python is more suitable for data science and automation, while JavaScript is more suitable for front-end and full-stack development. 1. Python performs well in data science and machine learning, using libraries such as NumPy and Pandas for data processing and modeling. 2. Python is concise and efficient in automation and scripting. 3. JavaScript is indispensable in front-end development and is used to build dynamic web pages and single-page applications. 4. JavaScript plays a role in back-end development through Node.js and supports full-stack development.

C and C play a vital role in the JavaScript engine, mainly used to implement interpreters and JIT compilers. 1) C is used to parse JavaScript source code and generate an abstract syntax tree. 2) C is responsible for generating and executing bytecode. 3) C implements the JIT compiler, optimizes and compiles hot-spot code at runtime, and significantly improves the execution efficiency of JavaScript.

JavaScript's application in the real world includes front-end and back-end development. 1) Display front-end applications by building a TODO list application, involving DOM operations and event processing. 2) Build RESTfulAPI through Node.js and Express to demonstrate back-end applications.

The main uses of JavaScript in web development include client interaction, form verification and asynchronous communication. 1) Dynamic content update and user interaction through DOM operations; 2) Client verification is carried out before the user submits data to improve the user experience; 3) Refreshless communication with the server is achieved through AJAX technology.

Understanding how JavaScript engine works internally is important to developers because it helps write more efficient code and understand performance bottlenecks and optimization strategies. 1) The engine's workflow includes three stages: parsing, compiling and execution; 2) During the execution process, the engine will perform dynamic optimization, such as inline cache and hidden classes; 3) Best practices include avoiding global variables, optimizing loops, using const and lets, and avoiding excessive use of closures.

Python is more suitable for beginners, with a smooth learning curve and concise syntax; JavaScript is suitable for front-end development, with a steep learning curve and flexible syntax. 1. Python syntax is intuitive and suitable for data science and back-end development. 2. JavaScript is flexible and widely used in front-end and server-side programming.

Python and JavaScript have their own advantages and disadvantages in terms of community, libraries and resources. 1) The Python community is friendly and suitable for beginners, but the front-end development resources are not as rich as JavaScript. 2) Python is powerful in data science and machine learning libraries, while JavaScript is better in front-end development libraries and frameworks. 3) Both have rich learning resources, but Python is suitable for starting with official documents, while JavaScript is better with MDNWebDocs. The choice should be based on project needs and personal interests.


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