classd

A minimal ES6 utility to compose classnames

classd is a fast, minimal JavaScript(ES6) utility for composing class names. It builds on ideas and philosophy similar to that of JedWatson's classnames. classd defaults to the idea of using ES6 template literals for composing class names. It also provides functions similar to classNames and classNames/dedupe for compatibility (with a minor behavioural difference in case of classNames/dedupe; detailed in a subsequent section).

It exports 4 functions:

1. classd (Tag for template literals, default)
2. classDedupe (Tag for template literals)
3. classdFn (Variadic function, for compatibility, similar to classNames)
4. classDedupeFn (Variadic function, for compatibility, similar to classNames/dedupe)

Installation

Install with npm, or Yarn:

# via npm
npm install --save classd

# or Yarn (note that it will automatically save the package to your `dependencies` in `package.json`)
yarn add classd

Use with ES6 modules (import)

// IMPORTING IN ES6
///////////////////

// ES6 import (default - classd tag for template literals)
import classd from 'classd';

// example use
const width = 1080;
const classes = classd`container padding-${{
    lg: width > 1280, 
    md: width > 960 && width < 1280,
    sm: width <= 960
}} margin-0 ${width > 960 && 'blue'} ${width < 960 && 'red'}`;
console.log(classes); // => 'container padding-md margin-0 blue'


// ES6 import any of the exported functions
import { classd, classDedupe, classdFn, classDedupeFn } from 'classd';

// example use (of classdFn)
const width = 1080;
const classes = classdFn ('container', {
    'padding-lg': width > 1280, 
    'padding-md': width > 960 && width < 1280,
    'padding-sm': width <= 960
}, (width > 960 && 'blue'), 'margin-0');
console.log(classes); // => 'container padding-md blue margin-0'

Use with commonjs (require)

// REQUIRING IN COMMONJS
////////////////////////

// commonjs require classd tag for template literals (default export)
const classd = require('classd').default

// commonjs require any of the exported functions
const { classd, classDedupe, classdFn, classDedupeFn } = require('classd');

// commonjs require classd module
const classd = require('classd'); // exports can be used as classd.classd, classd.classDedupe etc

Use in browser (from CDN)

// LOADING FROM CDN
///////////////////

<script src='https://cdn.jsdelivr.net/npm/classd@1.0/lib/index.js'></script>
<script type='text/javascript'>
    const { classd, classDedupe, classdFn, classDedupeFn } = window.classd;
    console.log(classd`container ${1 > 0 && 'blue'}`); // => 'container blue'
</script>

Project philosophy

We take the stability and performance of this package seriously.
Updates are thoroughly reviewed for performance impacts before being released.
We maintain a comprehensive test suite.
classd follows the SemVer standard for versioning.
There is also a Changelog.

Usage

classd tag for template literals

The classd tag processes the interpolation values in the template literal according to the following specification.

• Strings and numbers are valid values and are added to the output.
• It drops undefined, null, NaN and boolean values.
• If the value is an Array or an Iterable, it flattens the value and recursively processes the elements.
• If the value is an Object or a Map, it drops keys associated with falsy values and adds the remaining keys to the output.
• If the value is a function, it calls the function and adds its return value if that's valid
• It removes all unnecessary whitespace.

Examples

classd`foo bar`; // => 'foo bar'
classd`foo ${null && 'bar'}`; // => 'foo'
classd`foo-${true && 'bar'}`; // => 'foo-bar'
classd`${true} ${false}`; // => ''
classd`${{ foo: true, bar: false}}`; // => 'foo'
classd`${{foo: true}} ${{bar: true}} ${{baz: false}}`; // => 'foo bar'
classd`a ${[ 'b', 'c', false && 'd' ]}`; // => 'a b c'
classd`${['a', { b: 1, c: 0 }]}`; // 'a b'
classd`    a    b  \n  ${Array(10).fill(' ')} c`; // => 'a b c'

classdFn function

The classdFn follows the same specifications as the classd tag. Everything that's valid with classNames is also valid with classdFn. In addition, classdFn supports passing Maps, Sets, and other Iterables as arguments.

classdFn('foo', 'bar'); // => 'foo bar'
classdFn('foo', { bar: true }); // => 'foo bar'
classdFn({ 'foo-bar': true }); // => 'foo-bar'
classdFn({ 'foo-bar': false }); // => ''
classdFn({ foo: true }, { bar: true }); // => 'foo bar'
classdFn({ foo: true, bar: true }); // => 'foo bar'
classdFn('foo', { bar: true, duck: false }, 'baz', { quux: true }); // => 'foo bar baz quux'
classdFn(null, false, 'bar', undefined, 0, 1, { baz: null }, ''); // => 'bar 1'

var arr = ['b', { c: true, d: false }];
classdFn('a', arr); // => 'a b c'

classDedupe tag for template literals and classDedupeFn function

The classDedupe tag is an enhanced and about 60% slower version of the classd tag. It does everything that the classd tag does. In addition to that it checks for repeatations in case of classnames and ensures that each valid classname appears only once in the output string.

The classDedupeFn is the function equivalent of the classDedupe tag.

It differs from the classNames/dedupe in the behaviour that, the classNames/dedupe unsets a class if a configuration object appearing later in its arguments unsets it; whereas classDedupe does not unset a classname once it's set.

// classDedupe tag

classDedupe`a ${[ 'b', 'a', 'c' ]} c`; // => 'a b c'
classDedupe`${['a', { b: 1, a: 0 }]}`; // 'a b'

// classDedupeFn function

classDedupeFn('a', [ 'b', 'a', 'c' ], 'c b'); // => 'a b c'
classDedupeFn(['a', { b: 1, a: 0 }]); // 'a b'

Example usage with React

The classNames way (how to migrate to classd):

// before
// import classNames from 'classnames';

// after
import { classdFn } from 'classd';

class Button extends React.Component {
    // ...
    render () {

        // before
        // const btnClass = classNames({ ... });

        // after
        const btnClass = classdFn({
            btn: true,
            'btn-pressed': this.state.isPressed,
            'btn-over': !this.state.isPressed && this.state.isHovered
        });

        return <button className={btnClass}>{this.props.label}</button>;
    }
}

Using the classd tagged template literals:

import classd from 'classd';

const btnClass = classd`btn ${this.props.className} ${{
  'btn-pressed': this.state.isPressed,
  'btn-over': !this.state.isPressed && this.state.isHovered
}}`;

// or maybe directly in JSX

<Button 
    className={classd`
        btn 
        ${this.props.className} 
        ${this.state.pressed && 'btn-pressed'}
        ${!this.state.pressed && this.state.isHovered && 'btn-over'}
    `}
> 
    {this.props.label} 
</Button>

Polyfills needed to support older browsers

Array.isArray: see MDN for details about unsupported older browsers (e.g. <= IE8) and a simple polyfill.

License

MIT. Copyright (c) 2019 Ganesh Prasad.