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How to Minify CSS/JS Files (Using UglifyJS and UglifyCSS)

2.5 version
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How to Minify CSS/JS Files (Using UglifyJS and UglifyCSS)

UglifyJS is a JavaScript parser/compressor/beautifier toolkit. It can be used to combine and minify JavaScript assets so that they require less HTTP requests and make your site load faster. UglifyCSS is a CSS compressor/beautifier that is very similar to UglifyJS.

In this cookbook, the installation, configuration and usage of UglifyJS is shown in detail. UglifyCSS works pretty much the same way and is only talked about briefly.

Install UglifyJS

UglifyJS is available as an Node.js npm module and can be installed using npm. First, you need to install Node.js. Afterwards you can install UglifyJS using npm:

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$ npm install -g uglify-js

This command will install UglifyJS globally and you may need to run it as a root user.

Note

It's also possible to install UglifyJS inside your project only. To do this, install it without the -g option and specify the path where to put the module:

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$ cd /path/to/symfony
$ mkdir app/Resources/node_modules
$ npm install uglify-js --prefix app/Resources

It is recommended that you install UglifyJS in your app/Resources folder and add the node_modules folder to version control. Alternatively, you can create an npm package.json file and specify your dependencies there.

Depending on your installation method, you should either be able to execute the uglifyjs executable globally, or execute the physical file that lives in the node_modules directory:

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$ uglifyjs --help

$ ./app/Resources/node_modules/.bin/uglifyjs --help

Configure the uglifyjs2 Filter

Now we need to configure Symfony to use the uglifyjs2 filter when processing your JavaScripts:

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    # app/config/config.yml
    assetic:
        filters:
            uglifyjs2:
                # the path to the uglifyjs executable
                bin: /usr/local/bin/uglifyjs
    
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    <!-- app/config/config.xml -->
    <assetic:config>
        <!-- bin: the path to the uglifyjs executable -->
        <assetic:filter
            name="uglifyjs2"
            bin="/usr/local/bin/uglifyjs" />
    </assetic:config>
    
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    // app/config/config.php
    $container->loadFromExtension('assetic', array(
        'filters' => array(
            'uglifyjs2' => array(
                // the path to the uglifyjs executable
                'bin' => '/usr/local/bin/uglifyjs',
            ),
        ),
    ));
    

Note

The path where UglifyJS is installed may vary depending on your system. To find out where npm stores the bin folder, you can use the following command:

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$ npm bin -g

It should output a folder on your system, inside which you should find the UglifyJS executable.

If you installed UglifyJS locally, you can find the bin folder inside the node_modules folder. It's called .bin in this case.

You now have access to the uglifyjs2 filter in your application.

Configure the node Binary

Assetic tries to find the node binary automatically. If it cannot be found, you can configure its location using the node key:

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    # app/config/config.yml
    assetic:
        # the path to the node executable
        node: /usr/bin/nodejs
        filters:
            uglifyjs2:
                # the path to the uglifyjs executable
                bin: /usr/local/bin/uglifyjs
    
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    <!-- app/config/config.xml -->
    <assetic:config
        node="/usr/bin/nodejs" >
        <assetic:filter
            name="uglifyjs2"
            bin="/usr/local/bin/uglifyjs" />
    </assetic:config>
    
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    // app/config/config.php
    $container->loadFromExtension('assetic', array(
        'node' => '/usr/bin/nodejs',
        'uglifyjs2' => array(
                // the path to the uglifyjs executable
                'bin' => '/usr/local/bin/uglifyjs',
            ),
    ));
    

Minify your Assets

In order to use UglifyJS on your assets, you need to apply it to them. Since your assets are a part of the view layer, this work is done in your templates:

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    {% javascripts '@AppBundle/Resources/public/js/*' filter='uglifyjs2' %}
        <script src="{{ asset_url }}"></script>
    {% endjavascripts %}
    
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    <?php foreach ($view['assetic']->javascripts(
        array('@AppBundle/Resources/public/js/*'),
        array('uglifyj2s')
    ) as $url): ?>
        <script src="<?php echo $view->escape($url) ?>"></script>
    <?php endforeach ?>
    

Note

The above example assumes that you have a bundle called AppBundle and your JavaScript files are in the Resources/public/js directory under your bundle. This isn't important however - you can include your JavaScript files no matter where they are.

With the addition of the uglifyjs2 filter to the asset tags above, you should now see minified JavaScripts coming over the wire much faster.

Disable Minification in Debug Mode

Minified JavaScripts are very difficult to read, let alone debug. Because of this, Assetic lets you disable a certain filter when your application is in debug (e.g. app_dev.php) mode. You can do this by prefixing the filter name in your template with a question mark: ?. This tells Assetic to only apply this filter when debug mode is off (e.g. app.php):

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    {% javascripts '@AppBundle/Resources/public/js/*' filter='?uglifyjs2' %}
        <script src="{{ asset_url }}"></script>
    {% endjavascripts %}
    
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    <?php foreach ($view['assetic']->javascripts(
        array('@AppBundle/Resources/public/js/*'),
        array('?uglifyjs2')
    ) as $url): ?>
        <script src="<?php echo $view->escape($url) ?>"></script>
    <?php endforeach ?>
    

To try this out, switch to your prod environment (app.php). But before you do, don't forget to clear your cache and dump your assetic assets.

Tip

Instead of adding the filter to the asset tags, you can also globally enable it by adding the apply_to attribute to the filter configuration, for example in the uglifyjs2 filter apply_to: "\.js$". To only have the filter applied in production, add this to the config_prod file rather than the common config file. For details on applying filters by file extension, see Filtering Based on a File Extension.

Install, Configure and Use UglifyCSS

The usage of UglifyCSS works the same way as UglifyJS. First, make sure the node package is installed:

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$ npm install -g uglifycss

Next, add the configuration for this filter:

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    # app/config/config.yml
    assetic:
        filters:
            uglifycss:
                bin: /usr/local/bin/uglifycss
    
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    <!-- app/config/config.xml -->
    <assetic:config>
        <assetic:filter
            name="uglifycss"
            bin="/usr/local/bin/uglifycss" />
    </assetic:config>
    
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    // app/config/config.php
    $container->loadFromExtension('assetic', array(
        'filters' => array(
            'uglifycss' => array(
                'bin' => '/usr/local/bin/uglifycss',
            ),
        ),
    ));
    

To use the filter for your CSS files, add the filter to the Assetic stylesheets helper:

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    {% stylesheets 'bundles/App/css/*' filter='uglifycss' filter='cssrewrite' %}
         <link rel="stylesheet" href="{{ asset_url }}" />
    {% endstylesheets %}
    
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    <?php foreach ($view['assetic']->stylesheets(
        array('bundles/App/css/*'),
        array('uglifycss'),
        array('cssrewrite')
    ) as $url): ?>
        <link rel="stylesheet" href="<?php echo $view->escape($url) ?>" />
    <?php endforeach ?>
    

Just like with the uglifyjs2 filter, if you prefix the filter name with ? (i.e. ?uglifycss), the minification will only happen when you're not in debug mode.

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.