How to modify the javascript code of a web page

In order to modify the JavaScript of the web page, we need some prerequisite knowledge. First, you need to understand what JavaScript is.

JavaScript is a programming language used to create interactive and dynamic web pages. Unlike basic HTML and CSS, JavaScript allows web pages to interact with users, enabling more complex functionality.

If you want to modify the JavaScript of a web page, you need to know how to view the source code of the web page. In most browsers, you can open source view by right-clicking on a web page and selecting "View page source."

Once you open the source code of the web page, you need to find the JavaScript code. JavaScript code is usually placed inside the <script></script> tag, as shown below:

 
  <title>这是标题</title>
  <script>
   function myFunction() {
    document.getElementById("demo").innerHTML = "Hello World!";
   }
  </script>
 
 
  <p>点击按钮来改变这个文本。</p>
  <button>点击这里</button>
 

In this simple example, the JavaScript code is placed inside the <script></script> mark. This code defines a function named myFunction(), which will be called to modify the text when the user clicks the button.

Now, if you want to modify this JavaScript code, you can click on the line of code in the source code view, make your changes, and then save the file.

However, if you don't have the original code, or want to modify the JavaScript on a running web page, you will need to use the browser developer tools. Most browsers have a built-in developer tool that allows you to edit the JavaScript code on a web page.

In the Chrome browser, you can open the developer tools by pressing F12 or right-clicking on the webpage and selecting "Inspect". Select the "Sources" tab on the toolbar and select the JavaScript file you want to modify in the left menu. Next, you can make changes in the code editor and save the file.

After you modify the JavaScript code, you need to refresh the page to see the changes.

In short, modifying the JavaScript of a web page requires some prerequisite knowledge, including viewing the source code of the web page and using browser developer tools. If you need to modify JavaScript code, be sure to back up the original code to avoid errors.

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