⌘ K
js · whitespace · comments · live

Minify JavaScript (whitespace only)

Strips comments and collapses whitespace around operators and punctuation. Not a real mangler — pair with Terser or esbuild for production. Runs locally.

JavaScript Minifier
Input
85 B
6 lines
Output
51 B
1 lines
Status
ready
live
Ratio
0.60×
out/in
input · javascript
output · minified js
function sum(a,b){return a+b}console.log(sum(1,2));
Quick Start

How to minify JavaScript

String and template literals are pulled out first so the regex can safely collapse whitespace around the rest of the source.

  1. 01

    Paste JS

    Modern JS is fine — async/await, optional chaining, template strings.

    Parsing runs through Prettier’s standalone bundle (or the language-specific equivalent) loaded lazily — no parser ships until the tool is opened.

    jsPrettierASTstandalonelazy
    input · sourceraw · AST
    function f(){}
    loaded · parsedAST · ready
  2. 02

    Strings protected

    Quoted strings and template literals are replaced with placeholders so their contents survive intact.

    Indent width, tab style, and print-width re-format through a memoised pass — switching 2 → 4 spaces never re-parses, only re-prints.

    safeindentprint-widthmemoisedlive
    step · optionsstrings · live
    "x" → \x00P0\x00
    options applied · livelive
  3. 03

    Whitespace squashed

    Comments are dropped and whitespace around operators / punctuation collapses.

    The formatter is deterministic and idempotent: running it twice produces byte-identical output, which keeps diffs and git noise to a minimum.

    compactidempotentdeterministicdiff-cleanstable
    step · formattedwhitespace · ready
    function f(){return 1}
    formatted · liveidempotent
  4. 04

    Copy or download

    Drop the one-liner into a bundle stub or share via clipboard.

    Download writes a Blob with the language-appropriate extension; copy uses navigator.clipboard.writeText so the output preserves all whitespace exactly.

    exportclipboardbloblanguage MIMEclient-side
    ok · copiedready · done
    ✓ Copied
    shipped · ready to shipsuccess
Pro tips

Formatting tips that keep diffs sane

Pick one config and pin it

Inconsistent formatting causes diff churn. Commit .prettierrc / .editorconfig and enforce in CI.

Format on save

Editor integration is faster feedback than a pre-commit hook. Use both for belt-and-braces.

Idempotency matters

Running the formatter twice should produce identical output. Test this on a representative file.

Match the language community

Default to community conventions: 2 spaces for JS/CSS, 4 for Python, tabs for Go. Fights over indent are a productivity tax.

Print-width drives wrapping

80, 100, and 120 are the common targets. Wider lines parse fast but review slower side-by-side.

Don’t mix formatters and linters

Prettier handles whitespace; ESLint handles correctness. Disable overlapping rules to avoid fight-club configs.

Related toolsJS FormatterTS FormatterJSX FormatterTSX FormatterCSS MinifierHTML Minifier
Use Cases

When to minify JS

Inline snippets, build comparison, size budget.

Inline snippets

Trim a small JS payload before pasting into HTML. Idempotent: running the formatter twice produces byte-identical output, which is the foundation of a clean CI gate. Pair with a pre-commit hook so PRs arrive already formatted, focusing review on logic.

idempotent

Bookmarklet

Compress a bookmarklet body to fit inside javascript:. Pairs with EditorConfig + .prettierrc for end-to-end consistency. Whitespace-only changes vanish so reviewers see real diffs, and git blame stays honest about who wrote what.

CI-ready

Build comparison

Compare your bundler's output against this baseline. Output respects your indent width, tab style, and print-width — settings carry over for repeat runs. Switching 2-space to 4-space costs nothing in CPU but standardises an entire codebase.

diff-clean

Size budget

Eyeball whitespace savings vs. real minification. Format-on-save is the fastest feedback loop; CI is the safety net. Together they make inconsistent indentation a thing of the past and free up review cycles for genuine concerns.

PR-friendly

Quick share

Paste compact JS into chat or a gist. Whitespace-only changes don't trigger downstream content-hash invalidations, so CDN cache keys and CI cache layers stay warm. Real changes get all the rebuild budget.

review-ready

Demo embed

Bake JS into a static HTML demo with no build step. Pairs with linters (ESLint, Stylelint, pylint) that catch what formatting alone can't — bugs, unused imports, dead code. Each tool stays in its lane, and the codebase stays clean.

deterministic
FAQ

Frequently asked questions

No — Terser performs real mangling and dead-code elimination. This tool only strips comments and whitespace.
Regex literals are not specially detected — if a line looks like a regex divided by a comment marker, results may differ. Test before shipping.
Yes — they're protected with placeholders so internal whitespace survives.
Not generated. For production builds, use esbuild / Terser with source-map output.
No — the minifier runs locally in your browser tab.
Suggest a tool

Something missing?

Tell us what you need. We ship the top requests every two weeks.

Sent straight to the maintainers · no account needed
47 in queue·8 shipped this month
Request queued. Thanks!