JS Minifier

About JS minifier

The JS minifier shrinks JavaScript by removing comments, whitespace and line breaks. It reads the code as tokens, so strings, template literals and regular expressions are left untouched, and it keeps a line break wherever automatic semicolon insertion depends on it. It does not rename variables or restructure code, which makes it a safe fit for bookmarklets, inline snippets and tracking tags.

How to use it

1. Paste your script into the Original JavaScript box.
2. Leave Remove Comments, Remove Whitespace and Remove Newlines checked, or clear any you do not want. All three start checked.
3. Click Minify JavaScript. An unterminated string, template or comment is reported instead of being guessed at.
4. Look at the Original Size, Minified Size, Saved and Reduction figures in the summary card.
5. Copy the output from the Minified JavaScript box and run it once to confirm it still behaves.

A URL string, a division and a template literal

// fetch the page
const url = 'https://example.com/a';
const n = total / count; // average
function show(x) {
  return `Value: ${x}`;
}
show(url)

const url='https://example.com/a';const n=total/count;function show(x){return`Value: ${x}`;}show(url)

When to use it

• Compacting a bookmarklet so it fits comfortably in a browser bookmark.
• Shrinking a short inline script before pasting it into a page-builder or tag-manager field.
• Stripping explanatory comments from a snippet you are about to hand to a customer.
• Seeing roughly how much whitespace contributes to a small script's size.

Questions about JS minifier

Is a URL inside a string safe from the comment remover?

Yes. Strings, template literals and regular expressions are recognized before comments are looked for, so a quoted http address keeps its double slash and the text after it.

How does it tell division from a regular expression?

By the token before the slash. After a name, number, closing bracket or string the slash divides. After an operator, an opening bracket or a word such as return it starts a regular expression.

What happens to code that has no semicolons?

A line break is removed only where that cannot change the meaning. After return, before ++ or -- and between two statements that rely on automatic semicolon insertion, the break stays, or a semicolon is added after a closing brace.

Which comments are removed, and what if I turn that option off?

With Remove Comments on, every comment goes, including license banners. With it off, comments stay and the line breaks next to them are kept so a line comment cannot swallow the code that follows.

Will it rename variables or delete unused code?

No. Names, structure and dead code are untouched. Savings come only from whitespace and comments, which typically reduces a well-formatted file by a fraction rather than the large cuts a full minifier gives.

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