bem-it

A simple js object providing BEM class naming support and consistency for an individual or software team. Provides consistent BEM class names, and a clean api that doesn't bloat a component with untidy string concatenations.

The code has been thoroughly tested and test scripts are available, with source, in the npm-utils project here github. If you discover any bugs then please report. Thank you :).

Installation

Install from npm:

npm install @gtechdoodler/bem-it

How to Use

The examples provided are implemented in a React functional component...

Start by importing the BemIt object into your component, then create a new instance passing your component name to the constructor.

import React from 'react';
import BemIt from '@gtechdoodler/bem-it';

export default function() {
  const bem = new BemIt('Container');

  return (
    <div className={bem.out()}>
    </div>
  )
}

Calling bem.out() will output: Container

You always call .out() to output the class name value. Calling .out() also flushes the bem object, ensuring it's in a clean state, ready for your next statement.

Adding a Child Element

The examples from this point on, will include only the component, omitting the import statements.

export default function() {
  const bem = new BemIt('Container');

  return (
    <div className={bem.out()}>
      <div className={bem.el('content').out()}>
      </div>
    </div>
  )
}

Calling bem.el('content').out() will output: Container__content

Adding a Modifier to That Child Element

export default function() {
  const bem = new BemIt('Container');

  return (
    <div className={bem.out()}>
      <div className={bem.el('content').mod('show').out()}>
      </div>
    </div>
  )
}

Calling bem.el('content').mod('show').out() will output: Container__content Container__content--show

Notice we are following the official BEM standard here, outputting the Block__element and an additional Block__element--modifier to represent the modifier.

Multiple Modifiers as Array

For ternary operand false, pass an empty string, undefined, or null. This will ensure the exclusion of the modifier.

export default function({isFullScreen, isLoading, ...props}) {
  const bem = new BemIt('Container');
  const className = bem.mod([
    isFullScreen ? 'full-screen' : '',
    isLoading ? 'loading' : ''
  ]).out();

  return (
    <div className={className}>
    </div>
  )
}

Multiple Modifiers as Object

Anything falsy will be ignored.

export default function({isFullScreen, isLoading, ...props}) {
  const bem = new BemIt('Container');
  const className = bem.mod({
    'full-screen' isFullScreen,
    'loading': isLoading
  }).out();

  return (
    <div className={className}>
    </div>
  )
}

Include a Custom Class Name Passed as a Prop

To combine a class name passed as a prop, with bem output, you can import a function called addClass.

import BemIt, { addClass } from '@gtechdoodler/bem-it';

And implement as follows:

export default function({className, ...props}) {
  const bem = new BemIt('Container');

  return (
    <div className={addClass(className).before(bem)}>
    </div>
  )
}

If the className is falsy then it will be ignored, outputting only the bem class name. Also, you can flip the class names around, adding a custom class after a bem output, by calling addClass(className).after(bem).

Multiple Classes With a Single Statement

If you really must represent an element with mutiple class names, this is achieveable with chaining. Call and.

export default function() {
  const bem = new BemIt('Container');

  return (
    <div className={bem.out()}>
      <div className={bem.el('content').and.el('detail').out()}>
      </div>
    </div>
  )
}

Calling bem.el('content').and.el('detail').out() will output: Container__content Container__detail

TypeScript Declarations

These are exported, so if you're using TypeScript then have a play around... the api is light and chainable, so, if you want something wacky like:

bem.el('content').mod('show').and.el('content').el('summary').mod('highlight').out()

But please don't write code like this :).