npm package: @minko-fe/postcss-pxtorem
Description: A postcss plugin that converts px to rem.
Author: hemengke1997
Latest version: 1.5.0

# postcss-pxtorem

![npm][npm-img]

**English** | [中文](./README-zh.md)

A plugin for [PostCSS](https://github.com/ai/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](https://github.com/cuth/postcss-pxtorem)**

## [New Features](#-about-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

```bash
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

```js
// 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`](https://api.postcss.org/Input.html) 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](#propList)                                                                   |
| selectorBlackList | `(string \| RegExp)[]`                                              | []              | The selectors to ignore and leave as px. Refer to: [selectorBlackList](#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](https://developer.mozilla.org/en-US/docs/Web/CSS/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](#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

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

#### set rootValue

```css
/* 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](https://github.com/sindresorhus/query-string)

#### example

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

### disable the next line in css file

```css
.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:

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

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

## use with [modern-flexible](https://github.com/hemengke1997/modern-flexible)

### example

#### main.ts
```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](https://github.com/cuth/postcss-pxtorem)

[@tcstory/postcss-px-to-viewport](https://github.com/tcstory/postcss-px-to-viewport)

## Related

A CSS post-processor that converts px to viewport: [postcss-pxtoviewport](https://github.com/hemengke1997/postcss-pxtoviewport)

## Support

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

## License

MIT

[npm-img]: https://img.shields.io/npm/v/%40minko-fe/postcss-pxtorem.svg
[npm-download]: https://img.shields.io/npm/dm/%40minko-fe/postcss-pxtorem