PyCharm 2023.3 Help

Minifying JavaScript

Minification or compression means removing all unnecessary characters, such as spaces, new lines, comments, without changing the functionality of the source code. During development and debugging, these characters make code easier to read. At the production stage, they only increase the size of code to be transferred.

Most often compression is done as a step in your build process, with build tools like webpack. If you're not using build tools, you can use a stand-alone tool, such as UglifyJS.

To minify your code automatically, you need to install a minification tool and configure a File Watcher which will track changes to your files and run the minification tool.

By default, minification starts as soon as a JavaScript file in the File Watcher's scope is changed and saved. You can specify other events that invoke the tool. Learn more from File Watchers.

The generated minified code is stored in a separate file with the name of the source Javascript file and the extension min.js. The location of this generated file is defined in the Output paths to refresh field of the New Watcher dialog. However, in the Project Tree, the file with the minified code is shown under the source Javascript file which is displayed as a node. To change this default presentation, configure file nesting in the Project tool window.

The example below shows how you can use UglifyJS to minify your JavaScript code right from PyCharm.

Example: Compressing JavaScript with UglifyJS

To compress your code automatically, you need to install UglifyJS and configure a UglifyJS File Watcher which will track changes to your files and run the tool.

By default, minification starts as soon as a JavaScript file in the File Watcher's scope is changed and saved. You can specify other events that invoke UglifyJS. Learn more from File Watchers.

The generated minified code is stored in a separate file with the name of the source JavaScript file and the extension min.js. The location of this generated file is defined in the Output paths to refresh field of the New Watcher dialog. However, in the Project Tree, the file with the minified code is shown under the source JavaScript file which is displayed as a node. To change this default presentation, configure file nesting in the Project tool window.

Before you start

  1. Make sure you have Node.js on your computer.

  2. Make sure the JavaScript and TypeScript bundled plugin is enabled in the settings. Press Control+Alt+S to open the IDE settings and then select Plugins. Click the Installed tab. In the search field, type JavaScript and TypeScript. For more information about plugins, refer to Managing plugins.

  3. Make sure the File Watchers bundled plugin is enabled in the settings. Press Control+Alt+S to open the IDE settings and then select Plugins. Click the Installed tab. In the search field, type File Watchers. For more information about plugins, refer to Managing plugins.

Install UglifyJS globally

Create an UglifyJS File Watcher

  1. In the Settings dialog (Control+Alt+S), click File Watchers under Tools. The File Watchers page that opens shows the list of already configured File Watchers.

  2. Click Add button or press Alt+Insert and select the UglifyJS predefined template from the list.

    Create UglifyJS watcher: Click Add and select template

    The New Watcher dialog opens.

    Create UglifyJS watcher: New Watcher dialog with default settings
  3. In the Program field, specify the location of the UglifyJS executable file.

    If you installed UglifyJS through the Node Package Manager, PyCharm locates the package itself and fills in the field automatically with the uglifyjs alias. Otherwise, type the path manually or click App general open disk hover and select the file location in the dialog that opens.

  4. By default, the Scope field shows Project Files. To avoid minification of already minified files, configure a custom scope with the file:*js&&!file:*.min.* pattern, as described in Define a new scope.

    Then select the new scope from the Scopes list.

    Select custom scope
  5. Accept the other default File Watcher settings or reconfigure them, if necessary, as described in File Watchers, and click OK. PyCharm brings you back to the File Watchers page where the new File Watcher is added to the list:

    Create UglifyJS watcher: New Watcher added to the list
  6. Make sure the Enabled checkbox is selected.

    By default, the File Watcher will be available in the current project. To use it in other projects, select Global from the Level list.

Last modified: 11 December 2023