JavaScript Minifier/Formatter

Minify or Beautify JavaScript Code

Free online JavaScript minifier and formatter. Minify JavaScript code to reduce file size for production, or format (beautify) to improve readability and maintainability. Works entirely in your browser with complete privacy protection.

How to Use

Minify or format JavaScript in 3 steps:

Step 1: Enter JavaScript Code
Paste or type JavaScript code in the input area on the left
Step 2: Choose Processing Method
Click 'Minify' button to optimize for production, or 'Format' button to improve readability
Step 3: Copy Result
Copy the result displayed on the right. When minifying, the reduction percentage is also shown

All processing is performed in your browser. JavaScript code is not sent to servers.

JavaScript Minifier/Formatter

JavaScript Input

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JavaScript Output

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Use Cases

JavaScript Minifier/Formatter is useful in various scenarios:

1. Pre-Production Optimization

Minify JavaScript before deploying to production to reduce file size. Improves page load speed and reduces bandwidth costs. Typically achieves 30-60% size reduction.

2. Improve Readability of Third-Party JS

Format minified third-party JavaScript libraries to understand their contents. Makes debugging and customization easier. Convert minified versions of jQuery, React, Vue, etc. to readable format.

3. Code Review Preparation

Format minified JavaScript for easier team review. Improve code quality with consistent formatting and reduce review time.

4. Performance Optimization

Minify large JavaScript files to improve website performance. Contributes to better Lighthouse scores and Core Web Vitals, positively impacting SEO.

5. Legacy Code Maintenance

Format old JavaScript files with inconsistent formatting to a unified style. Improves maintainability and makes bugs easier to find.

What is JavaScript Minification/Formatting?

JavaScript minification and beautification/formatting are important techniques for code optimization and improved readability.

How JavaScript Minification Works

JavaScript minification reduces file size by removing comments, whitespace, line breaks, and shortening variable names. Functionality remains unchanged while only size is minimized. Example: `function hello(name) { return name; }` → `function hello(n){return n}`. Typically achieves 30-60% size reduction, significantly improving page load speed.

How JavaScript Formatting Works

JavaScript formatting adds appropriate line breaks and indentation to minified code to improve readability. Adds line breaks per function, arranges blocks clearly, and applies consistent indentation. Makes debugging, maintenance, and code review easier.

Browser-Based Processing Safety

This tool uses JavaScript to process code entirely in your browser. Since JavaScript code is not sent to servers, you can safely process confidential project code. Works offline with complete privacy protection.

Frequently Asked Questions

How much file size reduction can I expect from JavaScript minification?

Typically 30-60% file size reduction is possible. JavaScript with more comments and whitespace achieves higher reduction rates. For example, a 100KB JavaScript file can often be minified to 40-70KB, leading to significant page load speed improvements.

Can I restore minified JavaScript to its original state?

Minified JavaScript can be converted to a readable format using the 'Format' button. However, deleted comments and original variable names cannot be restored. Therefore, it's recommended to always keep a backup of the original file before minification.

Does this tool support TypeScript?

This tool is for standard JavaScript only. For TypeScript, please compile to JavaScript first before using. The TypeScript compiler (tsc) has minification options (--minify, etc.) that you can also consider.

Will JavaScript functionality be lost?

This tool performs basic minification and formatting, but may not work correctly with complex syntax or latest ECMAScript features. For professional production environments, we recommend using dedicated tools like Webpack, Terser, or UglifyJS.

Can it process large JavaScript files?

As long as your browser has sufficient memory, large files can be processed. Typically, JavaScript files of several MB work fine. However, very large files (10MB+) may slow down browser performance.

Are source maps generated?

Currently, source map generation is not supported. For professional development environments, we recommend using build tools like Webpack, Rollup, or Parcel with their source map features. This tool is optimal for simple minification and formatting.

Are JavaScript syntax errors checked?

This tool can detect basic syntax errors but does not provide complete validation. Syntax errors may prevent correct minification or formatting. We recommend checking syntax in advance using tools like ESLint.

Does minified JavaScript affect SEO?

JavaScript minification positively impacts SEO by improving page load speed. Google considers page speed as one of its ranking factors, contributing to improved Lighthouse scores and Core Web Vitals. Mobile user experience also significantly improves.