Classnames2
This is a fork of
classnames
package with es6 exports and other stuff.
Versions of this package should be remained the same as original classnames
.
A simple JavaScript utility for conditionally joining classNames together.
Installation
Install with npm, Bower, or Yarn:
npm:
npm install classnames2 --save
Yarn (note that yarn add
automatically saves the package to the dependencies
in package.json
):
yarn add classnames2
Usage
ES6 syntax
;; // => 'foo bar'
CommonJS
const classNames = ;// orconst classNames = ;
AMD
;
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.
; // => 'foo bar'; // => 'foo bar'; // => 'foo-bar'; // => ''; // => 'foo bar'; // => 'foo bar' // lots of arguments of various types; // => 'foo bar baz quux' // other falsy values are just ignored; // => 'bar 1'
Arrays will be recursively flattened as per the rules above:
var arr = 'b' c: true d: false ;; // => 'a b c'
Dynamic class names with ES2015
If you're in an environment that supports computed keys (available in ES2015 and Babel) you can use dynamic class names:
let buttonType = 'primary';;
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:
var Button = React;
You can express the conditional classes more simply as an object:
var classNames = ; var Button = React;
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:
var btnClass = ;
dedupe
version
Alternate 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:
var classNames = ; ; // => 'foo bar'; // => 'bar'
For standalone (global / AMD) use, include dedupe.js
in a <script>
tag on your page.
bind
version (for css-modules)
Alternate If you are using 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.
var classNames = ; var styles = foo: 'abc' bar: 'def' baz: 'xyz'; var cx = classNames; var className = ; // => "abc def xyz"
Real-world example:
/* components/submit-button.js */;;; let cx = classNames; { let text = thispropsstoresubmissionInProgress ? 'Processing...' : 'Submit'; let className = ; return <button className=className>text</button>; };
Polyfills needed to support older browsers
classNames >=2.0.0
Array.isArray
: see MDN for details about unsupported older browsers (e.g. <= IE8) and a simple polyfill.
Object.keys
: see MDN for details about unsupported older browsers (e.g. <= IE8) and a simple polyfill. This is only used in dedupe.js
.
License
MIT. Copyright (c) 2017 Jed Watson, Dmitry Zelenetskiy