pixrem

What is pixrem?

The pixrem npm package is a PostCSS plugin that converts pixel units to rem units in CSS. This is particularly useful for responsive web design, where rem units can provide more flexibility and scalability compared to fixed pixel units.

What are pixrem's main functionalities?

Convert px to rem

This feature converts pixel units to rem units in the provided CSS. The rootValue option specifies the root font size, which is used as the base for the conversion.

const postcss = require('postcss');
const pixrem = require('pixrem');

const css = 'body { font-size: 16px; }';
const options = { rootValue: 16 };

postcss([pixrem(options)])
  .process(css)
  .then(result => {
    console.log(result.css);
  });

Custom root value

This feature allows you to specify a custom root value for the conversion. In this example, the root value is set to 10, so 32px will be converted to 3.2rem.

const postcss = require('postcss');
const pixrem = require('pixrem');

const css = 'h1 { margin: 32px 0; }';
const options = { rootValue: 10 };

postcss([pixrem(options)])
  .process(css)
  .then(result => {
    console.log(result.css);
  });

Replace only specific properties

This feature allows you to replace only specific properties or at-rules. The options object can be configured to target specific CSS properties or at-rules for conversion.

const postcss = require('postcss');
const pixrem = require('pixrem');

const css = 'h1 { margin: 32px 0; padding: 16px; }';
const options = { rootValue: 16, replace: true, atrules: true, html: true, browsers: 'last 2 versions' };

postcss([pixrem(options)])
  .process(css)
  .then(result => {
    console.log(result.css);
  });

Other packages similar to pixrem

postcss-pxtorem

The postcss-pxtorem package is another PostCSS plugin that converts pixel units to rem units. It offers similar functionality to pixrem but includes additional options for controlling which properties are converted and supports media queries.

postcss-px-to-viewport

The postcss-px-to-viewport package converts pixel units to viewport units (vw, vh). While it serves a different purpose compared to pixrem, it is also used for responsive design by converting fixed units to scalable units based on the viewport size.

postcss-px-to-em

The postcss-px-to-em package converts pixel units to em units. Similar to pixrem, it helps in creating responsive designs by converting fixed units to relative units, but it uses em instead of rem.

README

Pixrem

PostCSS plugin that generates pixel fallbacks for rem units.

Installation

npm install --save pixrem

Usage

Pixrem is a CSS post-processor that, given CSS and a root em value, returns CSS with pixel unit fallbacks or replacements. It's based on browser data so only needed fallbacks will be added. Basically, it's for IE8 or less, and for IE9 & IE10 in the font shorthand property and in pseudo-elements.

Example

'use strict';
var fs      = require('fs');
var pixrem  = require('pixrem');
var postcss = require('postcss');

var css = fs.readFileSync('main.css', 'utf8');
var processedCss = postcss([pixrem]).process(css).css;

fs.writeFile('main.with-fallbacks.css', processedCss, function (err) {
  if (err) {
    throw err;
  }
  console.log('IE8, you\'re welcome.');
});

Pixrem takes this:

.sky {
  margin: 2.5rem 2px 3em 100%;
  color: blue;
}

@media screen and (min-width: 20rem) {
  .leaf {
    margin-bottom: 1.333rem;
    font-size: 1.5rem;
  }
}

And returns this:

.sky {
  margin: 80px 2px 3em 100%;
  margin: 2.5rem 2px 3em 100%;
  color: blue;
}

@media screen and (min-width: 20rem) {
  .leaf {
    margin-bottom: 1.333rem;
    font-size: 1.5rem;
  }
}

Options

Type: Object | Null Default: {rootValue: 16, replace: false, atrules: false, html: true, browsers: 'ie <= 8', unitPrecision: 3}

• rootValue the root element font size. Can be px, rem, em, %, or unitless pixel value. Pixrem also tries to get the root font-size from CSS (html or :root) and overrides this option. Use html option to disable this behaviour.
• replace replaces rules containing rems instead of adding fallbacks.
• atrules generates fallback in at-rules too (media-queries)
• html overrides root font-size from CSS html {} or :root {}
• browsers sets browser's range you want to target, based on browserslist
• unitPrecision control the significant digits after the decimal point

Contribute

Report bugs and feature proposals in the Github issue tracker. Run tests with npm test. In lieu of a formal styleguide, take care to maintain the existing coding style.

License

MIT