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					199 lines
				
				6.7 KiB
			| 
											3 years ago
										 | Classnames | ||
|  | =========== | ||
|  | 
 | ||
|  | [](https://www.npmjs.com/package/classnames) | ||
|  |  | ||
|  | [](https://www.npmjs.com/package/classnames) | ||
|  | [](https://www.npmjs.com/package/classnames) | ||
|  | [](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. |