jsmin

3.0.1 · maintenance · verified Sat Apr 11

jsmin is a Python library and command-line tool for minifying JavaScript code, based on Douglas Crockford's original jsmin.c. It removes unnecessary whitespace and comments to reduce file size. The current version is 3.0.1. The project is actively maintained, though the maintainer has stated they do not intend to add ECMAScript 6 (ES6) compatibility, indicating a focused maintenance cadence for its existing feature set.

Warnings

breaking Version 3.0.0 removed support for Python 2. If you require Python 2 compatibility, you must use version 2.2.2.
Fix: Upgrade to Python 3 or pin `jsmin` to version `2.2.2` for Python 2 projects: `pip install 'jsmin==2.2.2'`.
gotcha `jsmin` does not attempt to be compatible with ECMAScript 6 (ES6 / ES.next / Harmony) syntax. Using it on modern JavaScript code may result in incorrect minification or errors.
Fix: Ensure your JavaScript input is compatible with older ECMAScript standards (ES5-ish) or consider alternative minifiers for ES6+ code. For specific cases like template literals or certain quoted strings, the `quote_chars` parameter might offer limited help: `jsmin(code, quote_chars="'\"`")`.
gotcha `jsmin` expects syntactically correct JavaScript as input. Providing invalid JavaScript may lead to minification failures or corrupted output.
Fix: Always validate your JavaScript code using a linter or by running it in an environment (like a browser or Node.js) before feeding it to `jsmin`.
gotcha Comments starting with `/*!` (often called 'loud comments' or 'licence comments') are preserved during the minification process since version 2.2.0. Other comments are stripped.
Fix: Be aware of this behavior when expecting all comments to be removed. Use `/*!` for comments you wish to retain (e.g., copyright notices).

Install

pip install jsmin Install latest version

Imports

jsmin
```
from jsmin import jsmin
```

Quickstart

Minify a JavaScript string directly, or read from a file, process, and print the minified output. The primary function `jsmin()` takes a string of JavaScript code and returns the minified version.

from jsmin import jsmin

js_code = '''
// This is a comment
function greet(name) {
    console.log("Hello, " + name + "!");
}
greet("World");
'''

minified_js = jsmin(js_code)
print(minified_js)

# Example with a file (hypothetical, requires myfile.js to exist)
# try:
#     with open('myfile.js', 'r') as js_file:
#         minified_from_file = jsmin(js_file.read())
#         print(minified_from_file)
# except FileNotFoundError:
#     print("myfile.js not found for file example.")

view raw JSON →