ClassList

This module aims to match the behaviour of [Element#classList][classlist], without polyfilling it.

IE9 doesn't have the native classList, and other browsers have incomplete implementations. This module tries to bridge the gaps.

Installation

npm install classlist (or yarn add classlist)

Usage

This module is intended for use in the browser via a module bundler such as [Webpack][webpack] or [Browserify][browserify]. Sample usage:

``js
var classList = require('classlist')

var element = document.querySelector('#id')
var list = classList(element)

// Add a class:
list.add('foo')

// Remove a class:
list.remove('bar')

// Toggle a class:
list.toggle('baz')

// Replace class 'foo' with 'bar'
list.replace('foo', 'bar')

// Check if the element has a class:
if (list.contains('bar')) {
console.log('Element has class bar')
}
`

API

This module tries to follow the [native API][classlist] as closely as possible.

- list = new ClassList(element)

Constructor. Create a new ClassList object. new is optional.

`js
// Object style, "new"
var ClassList = require('classlist')
var list = new ClassList(element)

// Function style, no "new"
var classList = require('classlist')
var list = classList(element)
`

- list.item(index) or list[index]

Returns the class at the given index. Example:

`js
var div = document.createElement('div')
div.className = 'a b'
var list = classList(div)
list.item(0) // 'a'
list[1] // 'b'
`

- list.contains(class)

Returns true if the element has the given class; false otherwise.

- list.add(class1 [, class2 [, ... ]])

Adds one or more classes to the element associated with list. If the class is already present on the element, it is not added again.

- list.remove(class1 [, class2 [, ... ]])

Removes one or more classes from the element, if present.

- list.toggle(class [, force ])

Toggles the given class; removes the class if it is present, or adds the class if it is not present.

When force is true, the class is always added (i.e. it is equivalent to calling add). When force is false, the class is always removed (i.e. it is equivalent to calling remove). This can be useful when conditioning on an outcome; for example,

`js
list.toggle('not_empty', counter > 0)

// is equivalent to:
if (counter > 0) {
list.add('not_empty')
} else {
list.remove('not_empty')
}
`

Returns true if the class is now present, or false otherwise.

- list.replace(oldClass, newClass)

If oldClass is present on the element, it is replaced by newClass. If oldClass is not present, this method has no effect.

Returns true if the class was replaced, false` otherwise.

Browser support

This module has been tested for compatibility with IE8+, and may work in even older browsers. If it doesn't, open an issue.

License

MIT

[classlist]: https://developer.mozilla.org/docs/Web/API/Element/classList
[browserify]: http://browserify.org/
[webpack]: https://webpack.github.io/
[npm]: https://www.npmjs.com/