Sometimes it is necessary to allow users to upload multiple files on the page. The number is determined by the user. If the number is too large, it can be deleted. This function can be easily achieved using jQuery.
Let me show you the renderings first:
" width="374" style="max-width:90%" title="jQuery动态添加"/>
<!DOCTYPE html> <html> <head> <title>test.html</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <script type="text/javascript" src="jquery-1.6.4.min.js"></script> <script type="text/javascript"> //添加一行<tr> function add() { var content = "<tr><td>"; content += "<input type='file' name='file'><input type='button' value='Remove' onclick='remove(this)'>"; content +="</td></tr>" $("#fileTable").append(content); } //删除当前行<tr> function remove(obj) { $(obj).parent().parent().remove(); } </script> </head> <body> <form id="fileForm" action="" method="post" enctype="multipart/form-data"> <table id="fileTable"> <tr> <td> <input type="file" name="file"><input type="button" id="addButon" value="Add" onclick="add()"> </td> </tr> </table> </form> </body> </html>
Introducing various ways for JQuery to obtain the value in input type="text"
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>JQuery获取文本框的值</title> <meta http-equiv="Content-Type" content="text/html; charset=gb2312" /> <script src="jquery-1.5.1.min.js" type="text/javascript"></script> <script type="text/javascript"> //使用id的方式获取 $(document).ready(function(){ //1 $("#button_text1").click(function(){ var result1 = $("#input_text1").val(); alert("result1 = " + result1); }); //2 $("#button_text2").click(function(){ var result2 = $("input[id='input_text2']").val(); alert("result2 = " + result2); }); //3 $("#button_text3").click(function(){ var result3 = $("input[id='input_text3']").attr("value"); alert("result3 = " + result3); }); //4. 可以通过type的值来获取input中的值(未演示) /* $("#button_text4").click(function(){ var result4 = $("input[type='text']").val(); alert("result4 = " + result4); }); */ //5. 可以通过name的值来获取input中的值(未演示) /* $("#button_text5").click(function(){ var result5 = $("input[name='text']").val(); alert("result5 = " + result5); }); */ }); </script> </head> <body> <!-- 获取文本框的值:方式一 --> <p id="test1"> <input id="input_text1" type="text" value="test1" style="width: 100px;" /> <button id="button_text1">test1</button> </p> <!-- 获取文本框的值:方式二 --> <p id="test2"> <input id="input_text2" type="text" value="test2" style="width: 100px;" /> <button id="button_text2">test2</button> </p> <!-- 获取文本框的值:方式三 --> <p id="test3"> <input id="input_text3" type="text" value="test3" style="width: 100px;" /> <button id="button_text3">test3</button> </p> </body> </html>
More jQuery dynamically adds

The future trends of Python and JavaScript include: 1. Python will consolidate its position in the fields of scientific computing and AI, 2. JavaScript will promote the development of web technology, 3. Cross-platform development will become a hot topic, and 4. Performance optimization will be the focus. Both will continue to expand application scenarios in their respective fields and make more breakthroughs in performance.

Both Python and JavaScript's choices in development environments are important. 1) Python's development environment includes PyCharm, JupyterNotebook and Anaconda, which are suitable for data science and rapid prototyping. 2) The development environment of JavaScript includes Node.js, VSCode and Webpack, which are suitable for front-end and back-end development. Choosing the right tools according to project needs can improve development efficiency and project success rate.

Yes, the engine core of JavaScript is written in C. 1) The C language provides efficient performance and underlying control, which is suitable for the development of JavaScript engine. 2) Taking the V8 engine as an example, its core is written in C, combining the efficiency and object-oriented characteristics of C. 3) The working principle of the JavaScript engine includes parsing, compiling and execution, and the C language plays a key role in these processes.

JavaScript is at the heart of modern websites because it enhances the interactivity and dynamicity of web pages. 1) It allows to change content without refreshing the page, 2) manipulate web pages through DOMAPI, 3) support complex interactive effects such as animation and drag-and-drop, 4) optimize performance and best practices to improve user experience.

C and JavaScript achieve interoperability through WebAssembly. 1) C code is compiled into WebAssembly module and introduced into JavaScript environment to enhance computing power. 2) In game development, C handles physics engines and graphics rendering, and JavaScript is responsible for game logic and user interface.

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.


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