postcss-pxtorem

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A plugin for PostCSS that generates rem units from pixel units.

If you don't need the following new features, you can use the official library: postcss-pxtorem

New Features

• Dynamically override any postcss-pxtorem supported option in style files
• Dynamically disable transforming rem in style files.
• Compatible with vite, Solved the problem of px to rem failing after vite build.

Install

npm install postcss @minko-fe/postcss-pxtorem -D

Usage

Pixels are the easiest unit to use (opinion). The only issue with them is that they don't let browsers change the default font size of 16. This script converts every px value to a rem from the properties you choose to allow the browser to set the font size.

postcss.config.js

example

// postcss.config.js
import pxtorom from '@minko-fe/postcss-pxtorem'

export default {
  plugins: [
    pxtorom({
      rootValue: 16,
      selectorBlackList: ['some-class'],
      propList: ['*'],
      atRules: ['media'],
      // ...
    }),
  ],
}

options

Name	Type	Default	Description
rootValue	number | ((input: Input) => number)	16	Represents the root element font size or returns the root element font size based on the input parameter
unitToConvert	string	px	unit to convert, by default, it is px
unitPrecision	number	5	The decimal numbers to allow the REM units to grow to.
propList	string[]	['*']	The properties that can change from px to rem. Refer to: propList
selectorBlackList	(string | RegExp)[]	[]	The selectors to ignore and leave as px. Refer to: selectorBlackList
replace	boolean	true	Replaces rules containing rems instead of adding fallbacks.
atRules	boolean | string[]	false	Allow px to be converted in at-rules. Refer to At-rule
minPixelValue	number	0	Set the minimum pixel value to replace.
exclude	string | RegExp | ((filePath: string) => boolean) | null	/node_modules/i	The file path to ignore and leave as px. Refer to: exclude
include	string | RegExp | ((filePath: string) => boolean) | null	null	The file path to convert px to rem, in contrast to exclude, priority lower than exclude.
disable	boolean	false	disable plugin, used to disable plugin dynamically
convertUnit	ConvertUnit | ConvertUnit[] | false	false	convert unit when plugin process end

propList

• Values need to be exact matches.
• Use wildcard * to enable all properties. Example: ['*']
• Use * at the start or end of a word. (['*position*'] will match background-position-y)
• Use ! to not match a property. Example: ['*', '!letter-spacing']
• Combine the "not" prefix with the other prefixes. Example: ['*', '!font*']

selectorBlackList

• If value is string, it checks to see if selector contains the string.
  • ['body'] will match .body-class
• If value is regexp, it checks to see if the selector matches the regexp.
  • [/^body$/] will match body but not .body

exclude

• If value is string, it checks to see if file path contains the string.
  • 'exclude' will match \project\postcss-pxtorem\exclude\path
• If value is regexp, it checks to see if file path matches the regexp.
  • /exclude/i will match \project\postcss-pxtorem\exclude\path
• If value is function, you can use exclude function to return a true and the file will be ignored.
  • the callback will pass the file path as a parameter, it should returns a Boolean result.
  • function (file) { return file.includes('exclude') }

About new features

Dynamically set plugin options in css

disable plugin

/* pxtorem?disable=true */
.rule {
  font-size: 15px; // 15px
}

set rootValue

/* pxtorem?rootValue=32 */
.rule {
  font-size: 30px; // 0.9375rem
}

The above is just a simple example, you can set any of the options supported by postcss-pxtorem in the css file

You may have seen that the css comment is very much like the browser url?. That's right. For the specification, just refer to: query-string

example

/* pxtorem?disable=false&rootValue=32&propList[]=*&replace=false&selectorBlackList[]=/some-class/i */

disable the next line in css file

.rule {
  /* pxtorem-disable-next-line */
  font-size: 15px; // 15px
}

If you write 15PX (as long as it's not px), the plugin also ignores it, because unitToConvert defaults to px If you want to use PX to ignore and want the final unit to be px, you can:

// postcss.config.js
import pxtorem from '@minko-fe/postcss-pxtorem'

export default {
  plugins: [
    pxtorem({
      convertUnit: {
        source: /px$/i,
        target: 'px',
      },
    }),
  ],
}

use with modern-flexible

example

main.ts

import { flexible } from 'modern-flexible'

flexible({
  rootValue: 16,
  distinctDevice: [
    { isDevice: (w: number) => w < 750, UIWidth: 375, deviceWidthRange: [375, 750] },
    { isDevice: (w: number) => w >= 750, UIWidth: 1920, deviceWidthRange: [1080, 1920] },
  ],
})

❤️ Thanks

postcss-pxtorem

@tcstory/postcss-px-to-viewport

Related

A CSS post-processor that converts px to viewport: postcss-pxtoviewport

Support

If this has helped you, please don't hesitate to give a STAR, thanks! 😎

License

MIT