eqcss-parse

A Command-Line Parser for EQCSS Syntax

What does eqcss-parse do?

The main purpose of eqcss-parse is to consume the custom CSS-like syntax of EQCSS and parse it, transforming the selector(s), condition(s) and CSS styles in a JavaScript objects that can be loaded directly into EQCSS via EQCSS.register.

As an example, consider the following element query in EQCSS syntax which would make the html element green when any input on the page contains more than 3 characters:

@element input and (max-characters: 3) {
  html {
    background: lime;
  }
}

After running this through eqcss-parse our query has turned into something that looks like this:

EQCSS.register([{"selector":"input","conditions":[{"measure":"max-characters","value":"3","unit":null}],"style":" html { background: lime; } "},]);

Here the selector (input), the condition (max-characters), and the CSS styles have been turned into a JavaScript object. You'll also notice the output queries are wrapped in EQCSS.register() which would load them directly into the EQCSS plugin if it was running on the page.

Why would I use eqcss-parse?

Perhaps you want a workflow where you are free to write EQCSS in your source code and project files, but don't desire to output EQCSS's syntax in production. By using eqcss-parse during your build process you could end up with 100% standard JS objects so you don't need to include any non-standard syntax in production.

How do I use eqcss-parse

The simplest way to use this package is to install it via NPM with the following command:

npm install eqcss-parse

To convert an .eqcss file, or any file containing EQCSS syntax into JavaScript, use the eqcss-parse command. It can work with standard text input, as well as reading from a file, and output either to the command-line, or optionally to a file as well.

Reading from stdin

When using standard input, any way that you're able to pass a string of text to eqcss-parse will work. Here are some examples using echo, curl to download remote source code to process, and cat to parse the contents of multiple files as a batch:

echo "@element html { $this { background: lime; } }" | eqcss-parse

curl http://elementqueries.com | eqcss-parse

cat *.eqcss | eqcss-parse

Reading from a file

To read from a file, the first argument will automatically be used. In this example we will display the output of processing input.eqcss to the command-line:

eqcss-parse input.eqcss

Outputing to file

There are at least two ways of specifying an output file. If you are processing an individual file, the second argument you supply will automatically be used.

In this example, processing input.eqcss will produce output.js:

eqcss-parse input.eqcss output.js

If you have read from stdin instead of from a file you are not able to make use of the second argument because there is no first argument present. Suppose you were parsing queries from a.eqcss and b.eqcss and wanted to output both to c.js, we can use > to send output to a file:

cat a.eqcss b.eqcss | eqcss-parse > c.js