Minifying JavaScript with npx uglify-js#

While upgrading CodeMirror in Datasette I figured out how to minify JavaScript using uglify-js on the command line without first installing any teels, using npx (which downloads and executes a CLI tool while skipping the install step):

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npx uglify-js codemirror-5.57.0.js -o codemirror-5.57.0.min.js

One problem: this stripped out the LICENSE comment at the top of the file.

Turns out you can tell uglify-js not to strip comments that match a specific regular expression.

So I edited the CodeMirror file to use a single /* ... */ comment at the top of the file (instead of multiple // lines) and ran Uglify like this:

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npx uglify-js codemirror-5.57.0.js -o codemirror-5.57.0.min.js --comments '/LICENSE/'

For CSS I used clean-css-cli:

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npx clean-css-cli codemirror-5.57.0.css -o codemirror-5.57.0.min.css

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npx terser codemirror-5.57.0.js -o codemirror-5.57.0.min.js --comments '/LICENSE/'