cssmin.js in windows shell

October 29th, 2010. Tagged: CSS, JavaScript, performance

JavaScript can run virtually anywhere, including as a windows exe and the windows command line.

Say you have a JavaScript function foo()

function foo(input) {
  var output = input;
  // .. unicorns
  return output;

In order to make this a windows shell script you add at the and a way to read standard input and then write to the standard output:

(function () {
    var input  = WScript.StdIn.ReadAll(),
        output = foo(input);

Then you run this script, say foo.js, like:

$ cscript foo.js < input.txt

And it prints the output to the console.

If you want to read and print the code of foo.js itself you go:

$ cscript foo.js < foo.js
Microsoft (R) Windows Script Host Version 5.7
Copyright (C) Microsoft Corporation. All rights reserved.

function foo(input) {
  var output = input;

You can remove this "Microsoft (R) Windows..." stuff with //NoLogo parameter:

$ cscript //NoLogo foo.js < foo.js
function foo(input) {
  var output = input;


Alrighty, going back to the title of the post.

CSSMin.js is a port of YUICompressor's CSS minifier (source, hosted tool). Now adding a few lines at the end makes a windows shell script:

(function () {
    var src = WScript.StdIn.ReadAll();
    if (!src) {
        // help!
        WScript.StdOut.WriteLine("cscript //NoLogo cssmin.js < in.css > out.css");

Download it here.

Use it like:

$ cscript //NoLogo cssmin.js < in.css > out.css

Don't forget the //NoLogo or you'll end up with "Microsoft..." in your minified files

Random observation: "dude"[0] === "d" in most JS environments but is undefined in WSH (Windows Scripting Host). So "dude".substring(0, 1)

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