https://github.com/projectwallace/format-css
Fast, small, zero-config library to format CSS using basic rules.
https://github.com/projectwallace/format-css
css formatter prettier pretty-print
Last synced: about 1 month ago
JSON representation
Fast, small, zero-config library to format CSS using basic rules.
- Host: GitHub
- URL: https://github.com/projectwallace/format-css
- Owner: projectwallace
- License: mit
- Created: 2023-05-26T07:43:19.000Z (about 3 years ago)
- Default Branch: main
- Last Pushed: 2026-05-13T14:31:12.000Z (about 1 month ago)
- Last Synced: 2026-05-13T14:39:13.788Z (about 1 month ago)
- Topics: css, formatter, prettier, pretty-print
- Language: TypeScript
- Homepage: https://www.projectwallace.com/blog/tiny-css-formatter
- Size: 1.02 MB
- Stars: 18
- Watchers: 1
- Forks: 1
- Open Issues: 6
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# format-css
Fast, small, zero-config library to format CSS with basic [rules](#formatting-rules). The design goal is to format CSS in a way that makes it easy to inspect. Bundle size and runtime speed are more important than versatility and extensibility.
## Example output
```css
/* TURN THIS: */
@layer base.normalize{@media (dynamic-range:high) or (color-gamut:p3){@supports (color:color(display-p3 0 0 0)){:where(html){--link:color(display-p3 .1 .4 1);--link-visited:color(display-p3 .6 .2 1)}}}}@layer base.normalize{:where(html) :where(dialog){background-color:var(--surface-1)}}
/* INTO THIS: */
@layer base.normalize {
@media (dynamic-range: high) or (color-gamut: p3) {
@supports (color: color(display-p3 0 0 0)) {
:where(html) {
--link: color(display-p3 .1 .4 1);
--link-visited: color(display-p3 .6 .2 1);
}
}
}
}
@layer base.normalize {
:where(html) :where(dialog) {
background-color: var(--surface-1);
}
}
/* AND BACK AGAIN! */
```
## Installation
```
npm install @projectwallace/format-css
```
## Usage
```js
import { format } from '@projectwallace/format-css'
let old_css = '/* Your old CSS here */'
let new_css = format(old_css)
```
Need more examples?
- [StackBlitz example using CommonJS](https://stackblitz.com/edit/stackblitz-starters-phchci?file=index.js)
- [StackBlitz example using ES Modules](https://stackblitz.com/edit/stackblitz-starters-hrhsed?file=index.js)
### Partial formatters
The package also exports lower-level formatters for individual CSS constructs:
```js
import {
format_value,
format_declaration,
format_selector,
format_atrule_prelude,
} from '@projectwallace/format-css'
// Format a CSS value (e.g. the right-hand side of a declaration)
format_value(node.value)
// Format a single CSS declaration (property + value)
format_declaration(node)
// Format a single CSS selector
format_selector(node)
// Format an at-rule prelude string (e.g. the query part of @media)
format_atrule_prelude(node.prelude.text)
```
All of these accept the same options as `format()`. However, `tab_size` has no effect on them since they do not produce indented output.
```js
format_declaration(node, { minify: true })
format_selector(node, { minify: true })
```
## Formatting rules
1. Every **AtRule** starts on a new line
1. Every **Rule** starts on a new line
1. Every **Selector** starts on a new line
1. A comma is placed after every **Selector** that’s not the last in the **SelectorList**
1. Every **Block** is indented with 1 tab more than the previous indentation level
1. Every **Declaration** starts on a new line
1. Every **Declaration** ends with a semicolon (;)
1. An empty line is placed after a **Block** unless it’s the last in the surrounding **Block**
1. Multiline tokens like **Selectors, Values, etc.** are rendered on a single line
1. Unknown syntax is rendered as-is, with multi-line formatting kept intact
## Options
### Minify CSS
This package also exposes a minifier function since minifying CSS follows many of the same rules as formatting.
```js
import { format, minify } from '@projectwallace/format-css'
let minified = minify('a {}')
// which is an alias for
let formatted_mini = format('a {}', { minify: true })
```
### Tab size
For cases where you cannot control the tab size with CSS there is an option to override the default tabbed indentation with N spaces.
```js
import { format } from '@projectwallace/format-css'
let formatted = format('a { color: red; }', {
tab_size: 2,
})
```
## CLI
This library also ships a CLI tools that's a small wrapper around the library.
```
USAGE
format-css [options] [file...]
cat styles.css | format-css [options]
OPTIONS
--minify Minify the CSS output
--tab-size= Use N spaces for indentation instead of tabs
--help, -h Show this help
EXAMPLES
# Format a file
format-css styles.css
# Format with 2-space indentation
format-css styles.css --tab-size=2
# Minify
format-css styles.css --minify
# Via pipe
cat styles.css | format-css
```
## Related projects
- [Format CSS online](https://www.projectwallace.com/prettify-css) - See this formatter in action online!
- [Minify CSS online](https://www.projectwallace.com/minify-css) - See this minifier in action online!
- [CSS Analyzer](https://github.com/projectwallace/css-analyzer) - The best CSS analyzer that powers all analysis on [projectwallace.com](https://www.projectwallace.com)