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Beautifying JavaScript Code with Command Line Tools

If you work with JavaScript, you probably know that clean and well-structured code is essential for readability and maintenance. However, when dealing with minified or poorly formatted code, readability often goes out the window. Fortunately, you can use command line tools to beautify your JavaScript code efficiently, even if you’re working on different operating systems like Windows or Linux.

Problem Overview

In this post, we’ll explore how to beautify JavaScript code using command line tools. This approach is especially useful for developers who want to automate formatting as part of their workflow, such as when writing batch scripts.

Solution Steps

To beautify your JavaScript code via the command line, you can follow these steps:

Step 1: Choose a JavaScript Beautifier

The first step is to select a JavaScript beautifier. One popular option is JS Beautifier. This tool can take care of formatting your JavaScript code with ease.

Here’s how to get started:

  1. Download the beautifier file from the GitHub repository: beautify.js.
  2. Save it in a directory that you can easily access.

Step 2: Install Rhino JavaScript Engine

Next, you need to install the Rhino JavaScript engine developed by Mozilla. This engine allows you to execute JavaScript directly from the command line. Here’s how to install it:

  1. Download the Rhino ZIP file from the official Rhino site.

  2. Extract the contents of the ZIP file.

  3. Locate the js.jar file and place it in your Java classpath or in the Library/Java/Extensions folder on macOS.

    After completing these steps, you’ll be able to run scripts using the following command format:

    java -cp js.jar org.mozilla.javascript.tools.shell.Main name-of-script.js

Step 3: Create a Shell Script

Now that you have the beautifier and the Rhino engine set up, it’s time to create a shell script that utilizes both:

  1. Write a small shell script (let’s call it beautify.js) that will read in the JavaScript file you want to beautify and pass it to the beautifier.

  2. Here’s a simple example of what your script could look like:

    // original code
(function() { ... js_beautify code ... }());

// new code
print(global.js_beautify(readFile(arguments[0])));

Step 4: Run the Beautification Script

To beautify your JavaScript file, run your script through Rhino using the following command:

java -cp js.jar org.mozilla.javascript.tools.shell.Main beautify.js file-to-pp.js

Tips and Additional Information

  • Useful Functions: In the Rhino environment, you have access to additional functions that are helpful in a console context. For instance:

    • print() outputs a string to the console.
    • readFile() accepts a file path and returns the content of that file as a string.

  • Mix and Match: If you’re familiar with both Java and JavaScript, you can seamlessly integrate Java code within your Rhino scripts for more complex operations.

Conclusion

Now you have a step-by-step guide to beautifying JavaScript code using command line tools on any operating system. By setting up a simple script with the JS Beautifier and Rhino, you can ensure your code is always clean and readable.

For any JavaScript developer, maintaining code quality is of utmost importance, and using these command-line tools can significantly streamline your workflow. Happy coding!