README

A Bash script that uses terser to minify your JavaScript files and can be run in the root directory of your Magento 2 installation.

The script will minify all JavaScript files in the pub/static/frontend directory of your Magento 2 installation, except for those that are already minified or the requirejs-bundle-config.js file. The minification tasks can be run in parallel for increased performance.

Installation

You can install the package using Composer. Run the following command in your terminal:

composer require ibertrand/magento2-terser

Alternatively, you can download the files minify-m2-scripts.sh and minify-m2-scripts.cjs from the bin directory and save them wherever you want, as long as they stay in the same directory.

The script requires the terser command and Node.js to be available. If you don't have terser installed, you can install it globally with npm:

npm install terser -g

If you don't have npm installed, you need to install it first.

The script finds the terser package through the terser command, or failing that in npm's global node_modules. If terser was installed in a way that leaves neither, as pnpm and Volta do, set TERSER_PACKAGE to the directory of the terser package.

Usage

To run the script, open a terminal in the root directory of your Magento 2 installation and run:

vendor/bin/minify-m2-scripts.sh

This is assuming you installed the package using Composer. If you downloaded the files directly, you need to run minify-m2-scripts.sh with its full path.

By default, the script will minify all JavaScript files in the pub/static/frontend directory of your Magento 2 installation, except for those that are already minified or the requirejs-bundle-config.js file.

The original files will be replaced with the minified versions. If your M2 instance is in developer mode, this might alter files outside of the pub/static/frontend directory because of symlinks.

You can run the script with the -v or --verbose flag to display the name of each file that is being minified. Alternatively, you can run it with --no-progress-bar or with --silent, which includes --no-progress-bar.

Parallel execution

The script supports parallel execution of minification tasks to speed up the process. To specify the number of jobs to run in parallel, you can use the -j option followed by the number of jobs or --jobs= followed by the number of jobs.

For example, to run 3 jobs in parallel, you could use either of the below commands:

vendor/bin/minify-m2-scripts.sh -j3
vendor/bin/minify-m2-scripts.sh --jobs=3

--jobs=auto runs one job per CPU.

Each job is a worker thread that loads terser once and then minifies one file after another, so the time goes into minifying rather than into starting Node for every file.

Minifying only some themes

By default every theme in pub/static/frontend is minified. Magento deploys its own Blank and Luma themes alongside yours, and minifying them is wasted work if the store does not use them. To minify only the themes you serve, name each one with --theme=:

vendor/bin/minify-m2-scripts.sh --theme=Vendor/theme
vendor/bin/minify-m2-scripts.sh --theme=Vendor/theme --theme=Vendor/other

The script exits with an error if a named theme has not been deployed.

Subresource Integrity

Current Magento and Mage-OS releases record a Subresource Integrity hash for every deployed script, and put those hashes on the script tags of the payment pages. Minifying a file changes it, and a browser refuses a script whose hash no longer matches — on those pages only, so the checkout stops working while the rest of the shop looks fine.

Magento 2.4.7-p8 to 2.4.8-p5 keep these hashes in pub/static/<area>/sri-hashes.json; Magento 2.4.9 and Mage-OS keep them in pub/static/<area>/<Vendor>/<theme>/<locale>/sri-hashes.json. The script therefore updates the hash of every file it rewrites in whichever of these files exist, once all files are minified. Run it after setup:static-content:deploy, as before, and nothing else needs to change.

If an sri-hashes.json is not in the format described above, the script cannot update it. The scripts are minified by then, so the hashes in that file no longer match them: the script leaves the file as it was, prints an error, and exits with 1 without gzipping. Fix the file and run the script again, or run setup:static-content:deploy again. Where Magento keeps no such file, the script says so.

Magento 2.4.7 up to 2.4.7-p7 keeps the hashes in its cache instead, where the script cannot update them. To minify on those versions, flush the cache after running the script with bin/magento cache:flush: Magento then has no hashes until the next setup:static-content:deploy, and loads the payment pages' scripts without them.

Errors

A file that terser cannot parse is left as it was, and so is its SRI hash. The script prints ERROR: Failed to minify <file>, with the reason on stderr, and continues; it still exits with 0.

If a job itself fails, for example because Node runs out of memory, the script stops handing out files, lets the other jobs finish the file each one is working on, and exits with 1. Files that were not reached by then are left unminified; the SRI hashes of the files that were minified are still updated.

License

This project is licensed under the MIT License - see the LICENSE file for details.

ibertrand / magento2-terser

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