# JavaScript Minifier

> A free, browser-based tool that minifies, compresses and beautifies
> JavaScript using Terser 5. All processing happens client-side in
> JavaScript; the code is never uploaded to a server.

URL: https://seeb4coding.in/js/minifyjs/
Publisher: SeeB4Coding (https://seeb4coding.in/)
Engine: Terser 5.51.2 (BSD-2-Clause), loaded from the jsDelivr CDN
Price: Free, no sign-up, no usage limit.

## Modes

- **Minify** - remove whitespace and comments, shorten local names, and
  rewrite code into equivalent shorter forms.
- **Beautify** - reformat minified JavaScript with 2 or 4 space indentation.
  Mangled names cannot be restored.

## Syntax support

Modern JavaScript up to ES2024: arrow functions, classes, class fields,
private #members, static fields, async/await, async generators, optional
chaining (?.), nullish coalescing and assignment (??, ??=), BigInt,
destructuring, spread, template literals, import/export and dynamic import().

## Presets

- **Safe** - 1 compression pass, ES5 output, keeps class and function names,
  keeps debugger and console, keeps license comments.
- **Balanced** (default) - 2 passes, ES2020 output, drops debugger, keeps
  console, keeps license comments.
- **Aggressive** - 3 passes, ES2020 output, top-level mangling, drops console
  and debugger, removes all comments. Only for self-contained bundles.

Changing any preset option manually switches the preset to "Custom".

## Settings

- Output ECMAScript version: ES5, ES2015, ES2020.
- Compression passes: 1, 2 or 3.
- Comments: keep license comments (/*!, @license, @preserve), remove all,
  keep all.
- Toggles: compress, mangle names, top-level scope, drop console.*, drop
  debugger, keep class names, keep function names, source map, ES module,
  run as I type (inputs up to 300 KB).

## Output

- Minified or beautified code in a read-only editor with optional line wrap.
- Stats: original size, output size, gzip size of each (measured with the
  browser CompressionStream API), percentage saved, processing time and line
  counts.
- Source map (.map, version 3, with sourcesContent) and a matching
  //# sourceMappingURL comment when enabled.
- Parse errors show the message, line, column and a code excerpt, with a
  button that moves the cursor to the error.

## Other behaviour

- Paste, upload, or drag and drop .js, .mjs, .cjs or .jsx files. Several files
  are joined in selection order, each preceded by a comment with its file name.
  Maximum 10 MB in total.
- Copy output, download .min.js (or .js in beautify mode), download .map,
  use output as input.
- Draft input, settings and the last 20 runs are kept in browser
  localStorage only.
- Dark mode. Responsive layout with an Input/Output switcher on phones and
  tablets.
- Shortcuts: Ctrl/Cmd+Enter to run, Ctrl/Cmd+S to download the output.

## Related tools

- HTML Minifier: https://seeb4coding.in/html/htmlminify/
- JSON Beautifier & Formatter: https://seeb4coding.in/json/beautifyjson/
- JS Compiler: https://seeb4coding.in/js/jseditor/
- Online HTML Editor: https://seeb4coding.in/html/editor/