JavaScript Minifier
Quickly and easily minify JS code and optimize performance. Paste your JavaScript Code below.
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JavaScript Minification
JS minification removes whitespace, comments, and optional syntax, and optionally mangles variable names to produce the smallest possible script that behaves identically to the original.
What Minification Does
- Removes whitespace — spaces, tabs, newlines between tokens
- Strips comments — single-line
//and block/* */ - Shortens identifiers —
longVariableName→a - Removes dead code — unreachable branches
- Constant folding —
1 + 2→3at compile time
Typical Size Reduction
- Whitespace removal alone: 20–30%
- Plus mangling: 40–60%
- Plus gzip: 70–80% total reduction from original
- React's production bundle is ~3× smaller than development
What's the difference between minification and uglification?
Minification removes whitespace and comments. Uglification (obfuscation) additionally renames variables to short meaningless names. Tools like Terser and UglifyJS do both. Obfuscation makes code harder to reverse-engineer but not impossible — it's not a security measure.
How do I debug minified JavaScript?
Use source maps — minifiers can output a .map file that maps minified positions back to original source lines. Modern bundlers (Webpack, Vite, esbuild) generate source maps automatically, and browser DevTools use them to show the original code when debugging.
Should I minify third-party libraries?
Most popular libraries (React, Lodash, etc.) already ship pre-minified production builds. Minifying them again provides no benefit. Focus minification on your own application code, or use a bundler like esbuild or Rollup that handles everything in one pass.