199 lines
6.7 KiB
Markdown
199 lines
6.7 KiB
Markdown
|
Classnames
|
||
|
===========
|
||
|
|
||
|
[![NPM version](https://badgen.net/npm/v/classnames)](https://www.npmjs.com/package/classnames)
|
||
|
![Node.js CI](https://github.com/JedWatson/classnames/workflows/Node.js%20CI/badge.svg)
|
||
|
[![NPM Weekly Downloads](https://badgen.net/npm/dw/classnames)](https://www.npmjs.com/package/classnames)
|
||
|
[![License](https://badgen.net/npm/license/classnames)](https://www.npmjs.com/package/classnames)
|
||
|
[![Supported by Thinkmill](https://thinkmill.github.io/badge/heart.svg)](https://thinkmill.com.au/?utm_source=github&utm_medium=badge&utm_campaign=classnames)
|
||
|
|
||
|
A simple JavaScript utility for conditionally joining classNames together.
|
||
|
|
||
|
Install with [npm](https://www.npmjs.com/), [Bower](https://bower.io/), or [Yarn](https://yarnpkg.com/):
|
||
|
|
||
|
```bash
|
||
|
# via npm
|
||
|
npm install classnames
|
||
|
|
||
|
# via Bower
|
||
|
bower install classnames
|
||
|
|
||
|
# or Yarn (note that it will automatically save the package to your `dependencies` in `package.json`)
|
||
|
yarn add classnames
|
||
|
```
|
||
|
|
||
|
Use with [Node.js](https://nodejs.org/en/), [Browserify](https://browserify.org/), or [webpack](https://webpack.github.io/):
|
||
|
|
||
|
```js
|
||
|
var classNames = require('classnames');
|
||
|
classNames('foo', 'bar'); // => 'foo bar'
|
||
|
```
|
||
|
|
||
|
Alternatively, you can simply include `index.js` on your page with a standalone `<script>` tag and it will export a global `classNames` method, or define the module if you are using RequireJS.
|
||
|
|
||
|
### Project philosophy
|
||
|
|
||
|
We take the stability and performance of this package seriously, because it is run millions of times a day in browsers all around the world. Updates are thoroughly reviewed for performance impacts before being released, and we have a comprehensive test suite.
|
||
|
|
||
|
Classnames follows the [SemVer](https://semver.org/) standard for versioning.
|
||
|
|
||
|
There is also a [Changelog](https://github.com/JedWatson/classnames/blob/master/HISTORY.md).
|
||
|
|
||
|
## Usage
|
||
|
|
||
|
The `classNames` function takes any number of arguments which can be a string or object.
|
||
|
The argument `'foo'` is short for `{ foo: true }`. If the value associated with a given key is falsy, that key won't be included in the output.
|
||
|
|
||
|
```js
|
||
|
classNames('foo', 'bar'); // => 'foo bar'
|
||
|
classNames('foo', { bar: true }); // => 'foo bar'
|
||
|
classNames({ 'foo-bar': true }); // => 'foo-bar'
|
||
|
classNames({ 'foo-bar': false }); // => ''
|
||
|
classNames({ foo: true }, { bar: true }); // => 'foo bar'
|
||
|
classNames({ foo: true, bar: true }); // => 'foo bar'
|
||
|
|
||
|
// lots of arguments of various types
|
||
|
classNames('foo', { bar: true, duck: false }, 'baz', { quux: true }); // => 'foo bar baz quux'
|
||
|
|
||
|
// other falsy values are just ignored
|
||
|
classNames(null, false, 'bar', undefined, 0, 1, { baz: null }, ''); // => 'bar 1'
|
||
|
```
|
||
|
|
||
|
Arrays will be recursively flattened as per the rules above:
|
||
|
|
||
|
```js
|
||
|
var arr = ['b', { c: true, d: false }];
|
||
|
classNames('a', arr); // => 'a b c'
|
||
|
```
|
||
|
|
||
|
### Dynamic class names with ES2015
|
||
|
|
||
|
If you're in an environment that supports [computed keys](https://www.ecma-international.org/ecma-262/6.0/#sec-object-initializer) (available in ES2015 and Babel) you can use dynamic class names:
|
||
|
|
||
|
```js
|
||
|
let buttonType = 'primary';
|
||
|
classNames({ [`btn-${buttonType}`]: true });
|
||
|
```
|
||
|
|
||
|
### Usage with React.js
|
||
|
|
||
|
This package is the official replacement for `classSet`, which was originally shipped in the React.js Addons bundle.
|
||
|
|
||
|
One of its primary use cases is to make dynamic and conditional `className` props simpler to work with (especially more so than conditional string manipulation). So where you may have the following code to generate a `className` prop for a `<button>` in React:
|
||
|
|
||
|
```js
|
||
|
class Button extends React.Component {
|
||
|
// ...
|
||
|
render () {
|
||
|
var btnClass = 'btn';
|
||
|
if (this.state.isPressed) btnClass += ' btn-pressed';
|
||
|
else if (this.state.isHovered) btnClass += ' btn-over';
|
||
|
return <button className={btnClass}>{this.props.label}</button>;
|
||
|
}
|
||
|
}
|
||
|
```
|
||
|
|
||
|
You can express the conditional classes more simply as an object:
|
||
|
|
||
|
```js
|
||
|
var classNames = require('classnames');
|
||
|
|
||
|
class Button extends React.Component {
|
||
|
// ...
|
||
|
render () {
|
||
|
var btnClass = classNames({
|
||
|
btn: true,
|
||
|
'btn-pressed': this.state.isPressed,
|
||
|
'btn-over': !this.state.isPressed && this.state.isHovered
|
||
|
});
|
||
|
return <button className={btnClass}>{this.props.label}</button>;
|
||
|
}
|
||
|
}
|
||
|
```
|
||
|
|
||
|
Because you can mix together object, array and string arguments, supporting optional `className` props is also simpler as only truthy arguments get included in the result:
|
||
|
|
||
|
```js
|
||
|
var btnClass = classNames('btn', this.props.className, {
|
||
|
'btn-pressed': this.state.isPressed,
|
||
|
'btn-over': !this.state.isPressed && this.state.isHovered
|
||
|
});
|
||
|
```
|
||
|
|
||
|
|
||
|
### Alternate `dedupe` version
|
||
|
|
||
|
There is an alternate version of `classNames` available which correctly dedupes classes and ensures that falsy classes specified in later arguments are excluded from the result set.
|
||
|
|
||
|
This version is slower (about 5x) so it is offered as an opt-in.
|
||
|
|
||
|
To use the dedupe version with Node.js, Browserify, or webpack:
|
||
|
|
||
|
```js
|
||
|
var classNames = require('classnames/dedupe');
|
||
|
|
||
|
classNames('foo', 'foo', 'bar'); // => 'foo bar'
|
||
|
classNames('foo', { foo: false, bar: true }); // => 'bar'
|
||
|
```
|
||
|
|
||
|
For standalone (global / AMD) use, include `dedupe.js` in a `<script>` tag on your page.
|
||
|
|
||
|
|
||
|
### Alternate `bind` version (for [css-modules](https://github.com/css-modules/css-modules))
|
||
|
|
||
|
If you are using [css-modules](https://github.com/css-modules/css-modules), or a similar approach to abstract class "names" and the real `className` values that are actually output to the DOM, you may want to use the `bind` variant.
|
||
|
|
||
|
_Note that in ES2015 environments, it may be better to use the "dynamic class names" approach documented above._
|
||
|
|
||
|
```js
|
||
|
var classNames = require('classnames/bind');
|
||
|
|
||
|
var styles = {
|
||
|
foo: 'abc',
|
||
|
bar: 'def',
|
||
|
baz: 'xyz'
|
||
|
};
|
||
|
|
||
|
var cx = classNames.bind(styles);
|
||
|
|
||
|
var className = cx('foo', ['bar'], { baz: true }); // => "abc def xyz"
|
||
|
```
|
||
|
|
||
|
Real-world example:
|
||
|
|
||
|
```js
|
||
|
/* components/submit-button.js */
|
||
|
import { Component } from 'react';
|
||
|
import classNames from 'classnames/bind';
|
||
|
import styles from './submit-button.css';
|
||
|
|
||
|
let cx = classNames.bind(styles);
|
||
|
|
||
|
export default class SubmitButton extends Component {
|
||
|
render () {
|
||
|
let text = this.props.store.submissionInProgress ? 'Processing...' : 'Submit';
|
||
|
let className = cx({
|
||
|
base: true,
|
||
|
inProgress: this.props.store.submissionInProgress,
|
||
|
error: this.props.store.errorOccurred,
|
||
|
disabled: this.props.form.valid,
|
||
|
});
|
||
|
return <button className={className}>{text}</button>;
|
||
|
}
|
||
|
};
|
||
|
|
||
|
```
|
||
|
|
||
|
|
||
|
## Polyfills needed to support older browsers
|
||
|
|
||
|
#### `classNames >=2.0.0`
|
||
|
|
||
|
`Array.isArray`: see [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/isArray) for details about unsupported older browsers (e.g. <= IE8) and a simple polyfill.
|
||
|
|
||
|
|
||
|
## LICENSE [MIT](LICENSE)
|
||
|
|
||
|
Copyright (c) 2018 Jed Watson.
|
||
|
Copyright of the Typescript bindings are respective of each contributor listed in the definition file.
|