How to compress a JavaScript file for production

1. Paste the JS

   Drop the readable JS into the "JS" field. Whole modules or single functions are fine; the minifier walks the AST so it understands scopes, hoisting, and arrow vs function syntax.

2. Press Run

   Result returns `minified` and `savedPercent` (how much smaller than the input). Typical wins: 35–55% on hand-written JS, less on already-treeshaken bundles. Long identifier names lose the most.

3. What's removed

   Comments, whitespace, dead branches the minifier can prove unreachable. Identifiers get mangled to single letters where safe (locals; exports stay readable). String literals, regex bodies, and template literals are NOT touched.

4. Don't skip source maps

   When you minify for deployment, generate a sourcemap so production stack traces stay readable. This tool is a quick paste-and-go minifier — for a real build use terser or esbuild with `--sourcemap` and ship the `.map` next to the bundle.