bem-cn

Friendly BEM class names generator. Great for React.

Bem-cn (aka BEM Class Name) is extra small (minified+gzipped less than 1Kb) and extremely simple client-side library and Node.js module.

Inspired by b_.

Why?

Why I created yet another node module?

I spent a lot of time finding BEM class name generator, that meets my needs:

• Simple usage with React
• Support modifiers without value
• Mix multiple blocks
• Friendly chainable API

But now (March 2015) I can't find it. That's why.

Install

With Node.js:

npm i --save bem-cn

Or use Bower for install:

bower install --save bem-cn

Works with webpack and browserify:

var block = require('bem-cn');

Usage

Let's try:

var b = block('button');

// Block
b; // 'button'
b(); // 'button'

// Element
b('icon'); // 'button__icon'

// Modifier
b({ type: 'text' });  // 'button button_type_text'
b({ type: 'text' }, { type: 'colored' }); // 'button button_type_text button_type_colored'
b({ onlykey: true });  // 'button button_onlykey'
b({ without: false });  // 'button'

// Mix
b('icon').mix('another'); // 'button__icon another'
b('icon').mix([ 'one', 'two' ); // 'button__icon one two'
b('icon').mix({ one: true, two: false, three: true }); // 'button__icon one three'
b('icon').mix(b); // 'button__icon button'

// States
// As SMACSS states: https://smacss.com/book/type-state
b.state({ hidden: true }); // 'button is-hidden'
b.state({ hidden: false }); // 'button'
b.state({ hidden: true, error: true }); // 'button is-hidden is-error'

// Custom separators
block.setup({
    el: '~~',
    mod: '-'
});

var b = block('block');

b('element'); // 'block~~element'
b({ mod: 'value' }); // 'block block-mod-value'

Usage with JSX:

var block = require('bem-cn'),
    b = block('popup');

var Popup = React.createClass({
    render: function() {
        return (
            <div className={b.mix(this.props.mix)}>
            	<span className={b('icon')} />
            	<div className={b('content', { skin: this.props.skin })}>
            		{this.props.children}
            	</div>
            </div>
        );
    }
});

React.render(<Popup mix="another" skin="bright" />, target);
/*
<div class="popup another">
	<span class="popup__icon"></span>
	<div class="popup__content popup__content_skin_bright">
	</div>
</div>
 */