A basic variable replacement preprocessor for CSS files
JavaScript
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Varr

Description

Varr is a basic variable replacement preprocessor. It's intended for use with CSS files, turning this source CSS code:

$brand_colour: #777;
$brand_font: Helvetica;
---

body {
    background: $brand_colour;
    font-family: $brand_font;
    border: 1px solid $brand_colour;
}

into this:

body {
    background: #777;
    font-family: Helvetica;
    border: 1px solid #777;
}

Caveats

  • Varr is ridiculously basic in it's implementation & functionality. Coming in at ~100 lines of JavaScript, this is not meant to be any sort of Sass alternative, let alone a competitor.
  • This tiny tool was born out of redesigning my personal site and just wanting a quick way to add variables to my single CSS file.
  • This tool currently only works with one file. Multiple files will be added in the near future, I just can't say when.
  • Tl;dr - Re-inventing the wheel, albeit a small wheel, can be a bunch of fun.

Installation

Available on npm.

For command line installation:

npm install varr -g

Setup

Varr expects certain config at the top of your source CSS file. The expected format looks like so:

$foo: bar;
$someFont: Arial;
---

body {
    background: $foo;
    font-family: $someFont;
}

If you've ever used Sass, then this should look fairly familiar. A set of key/values separated by line breaks.

The only other thing that is very key, is the 3 dashes below the variables. This tells Varr when to stop looking for config variables. Don't forget these. And always put the variables at the top of the file.

Usage

Usage is dead simple. First cd to a folder with a CSS file in it. Now we can run Varr.

The most basic command is:

varr -i style.css

This will take style.css as an input, process & replace the variables, and then output the new, compiled CSS file to dist/style.css. Varr outputs the new CSS file relative to where you're running the command (inside a folder called "dist"). If you'd like to change the output path, read on...

varr -i style.css -o production/live.css

Will take the same "style.css" input file, but once it's processed it, will output it to a folder called "production" (no need to create this folder) and call the new file "live.css".

Lastly, Varr does support file watching, so this command:

varr -i style.css -o production/live.css watch

Will run the tool each time you hit save on "style.css".

As per usual, errors are output to the command line, but should you hit save prematurely and it errors, just fix up your file and re-save it. The program should not break.

Contributing

I'll be using this tool for my own small projects, but I figured some people might benefit from something lightweight as well, so it became a public tool published on npm. I'd be really delighted if people did want to improve it, fix some stuff, etc...but we really don't need to re-create Sass.