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javascript fails in Jsp

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Release： 2023-05-21 11:46:37

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JSP is a server-side Web application development platform written in Java language, which can generate dynamic web content. At the same time, embedding JavaScript code in JSP pages can achieve richer interactive effects and practical functions.

However, in actual development work, we often encounter some problems about JSP and JavaScript. This article will discuss the interaction principles between JSP and JavaScript, common problems with JavaScript in JSP and their solutions.

1. The interaction principle between JSP and JavaScript

The JSP page responds to client requests through the server, while JavaScript runs on the client. Therefore, when embedding JavaScript code in a JSP page, it is necessary to ensure that the JavaScript code is correctly executed by the client.

The following is an example of JavaScript code embedded in a simple JSP page:

<html>
   <head>
      <title>JSP页面中的JavaScript示例</title>
   </head>
   <body>
      <h1>欢迎来到JSP世界！</h1>
      <script type="text/javascript">
         alert("Hello,World!");
      </script>
   </body>
</html>

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In this example, the JavaScript code in the <script> tag is interpreted After parsed by the browser, a alert("Hello, World!"); JavaScript function will be generated. When the browser parses this function, a window will pop up showing "Hello, World!".

2. Common problems with JavaScript in JSP and their solutions

JavaScript code is parsed by the JSP server

When embedding JavaScript code in JSP, It may cause JavaScript code to be parsed by the JSP server and fail to execute correctly on the client.

Solution:
Comments using <%-- and --%> tags can prevent JavaScript code from being parsed by the server. An example is as follows:

<html>
   <head>
      <title>JSP页面中的JavaScript示例</title>
   </head>
   <body>
      <h1>欢迎来到JSP世界！</h1>
      <%--
      <script type="text/javascript">
         alert("Hello,World!");
      </script>
      --%>
   </body>
</html>

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The file path referenced by JavaScript is incorrect

When referencing a JavaScript file in a JSP page, if the file path is incorrect, the JavaScript code will not be able to loaded, thus failing to execute correctly on the client.

Solution:
Use relative paths to specify the correct file path. An example is as follows:

<html>
   <head>
      <title>JSP页面中的JavaScript示例</title>
      <script type="text/javascript" src="js/demo.js"></script>
   </head>
   <body>
      <h1>欢迎来到JSP世界！</h1>
   </body>
</html>

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In this example, the src attribute specifies the location of the JavaScript file using a relative path.

Syntax errors in JavaScript code

When embedding JavaScript code in a JSP page, if there are syntax errors in the code, the JavaScript code will not be displayed on the client. Executed correctly.

Solution:
Before embedding JavaScript code, you can first write the code in a separate JS file, and introduce this JS file in the HTML head tag to let the browser interpret and run this script. code to avoid syntax errors.

The JavaScript code in the JSP page conflicts with other JavaScript libraries

There may be conflicts between the JavaScript code embedded in the JSP page and other JavaScript libraries introduced in the page A conflict occurs, causing the JSP page to fail to run properly.

Solution:
You can use jQuery.noConflict() or $.noConflict() in the code to resolve conflicts with other JavaScript libraries . An example is as follows:

<script type="text/javascript" src="js/jquery.min.js"></script>
<script type="text/javascript">
   $.noConflict();
   // your code here
</script>

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In this example, $.noConflict() resolves the conflict with the jQuery library.

3. Conclusion

This article introduces the interaction principle between JSP and JavaScript, as well as common problems and solutions for embedding JavaScript code in JSP. When we encounter these problems during the development process, we can solve them according to the methods given in this article. At the same time, we also need to continue to learn and accumulate experience, improve our development level, and create more efficient, stable and reliable web applications.

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