In modern web development, JavaScript (JS for short) has become an indispensable part. JS can not only achieve dynamic effects on web pages, but also facilitate code modularization and reuse through external JavaScript files. This article explains how to use external JavaScript files and the benefits of using external JavaScript files.
First, we need to understand what an external JavaScript file is. External JavaScript files refer to saving JS code in a separate JavaScript file and introducing it in HTML through the <script></script> tag. External JS files have separate file paths and file names, and references can be shared across multiple HTML pages.
Next, let’s take a look at how to use external JavaScript files.
Step 1: Create an external JavaScript file
To use an external JavaScript file, you need to create an independent .js file first. You can create files through any editor, such as Notepad or Sublime Text. Write your JS code in a file and save the file as a standalone JS file, such as myscript.js.
Step 2: Introduce external JavaScript files into HTML
To introduce external JavaScript files into HTML files, you need to use the <script></script> tag. There are two attributes in the tag: src and type. The src attribute is used to specify the path of the JS file, and the type attribute is used to specify the type of the JS file, usually set to text/javascript. The following is a code example that introduces an external JavaScript file:
<!DOCTYPE html> <html> <head> <script src="myscript.js" type="text/javascript"></script> </head> <body> </body> </html>
The above code will introduce an external file named myscript.js in the tag of HTML JavaScript files. In this way, when the HTML is loaded, the JS file will also be loaded and the code in it will be executed.
Benefit Analysis: Benefits of Using External JavaScript Files
Now, let’s take a look at the benefits of using external JavaScript files.
- Improve code maintainability
Separating JS code into independent files can make the code more structured and easier to maintain. If you want to modify the code, you only need to modify a separate file instead of modifying the code in each HTML file. - Facilitates code reuse
If you have multiple HTML files that need to use the same JS code, then using external JavaScript files can easily achieve code reuse. Just introduce the same JS file in different HTML files. - Reduce the loading time of the code
Using external JS files can reduce the size of the HTML file, thereby reducing the loading time of the page. Because JS files can be cached, if multiple HTML pages reference the same JS file, then when the first page loads the JS file, it will already be cached, so that the file will not be downloaded again on subsequent page loads.
Summary
In this article, we learned how to use external JavaScript files and the benefits of using external JavaScript files. For larger projects, using external JavaScript files can make the code more structured, easier to maintain and reuse, and can also help reduce page load times. Therefore, it is necessary to use external JavaScript files in the project. It is recommended that you modularize the JavaScript code as much as possible to better manage and maintain the code.
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