4ormat / bem

A BEM class name generator to use with React

BEM

A small utility for creating old-school BEM classes, especially in a React context.

NOTE: Maintained for internal use only.

Quickstart

Given a component definition

import { bem } from "bem";

export const AlertBar = ({ level, message }) => {
  const b = bem("alert-bar");

  return (
    <div className={b.e("wrapper")}>
      <p className={b.e("message").m(level)}>{message}</p>
    </div>
  );
};

Rendering

<AlertBar message="Hello!" level="warning" />

Yields

<div class="alert-bar__wrapper">
  <p class="alert-bar__message alert-bar__message--warning">Hello!</p>
</div>

Examples

Simple Elements

• bem('alert-bar').e('wrapper') yields "alert-bar__wrapper"

String Modifiers

• bem('alert-bar').m('warning') yields "alert-bar alert-bar--warning"
• bem('alert-bar').e('wrapper').m('warning') yields "alert-bar__wrapper alert-bar__wrapper--warning"

Array Modifiers

• bem('alert-bar').m(['warning', 'condensed']) yields "alert-bar alert-bar--warning alert-bar--condensed"
• bem('alert-bar').e('wrapper').m(['warning', 'condensed']) yields "alert-bar__wrapper alert-bar__wrapper--warning" alert-bar__wrapper--condensed

Object Modifiers

• bem('alert-bar').m({ warning: true, condensed: true }) yields "alert-bar alert-bar--warning alert-bar--condensed"
• bem('alert-bar').e('wrapper').m({ warning: true, expanded: false }) yields "alert-bar__wrapper alert-bar__wrapper--warning"