vue-bem-cn

Simple BEM-style class name generator for Vue.JS 2.*

Table of Contents

• Quick example
• Installation
• Usage
• API

Quick example

Live demo: codepen

Block ui-button. Vue Single File Component:

<script>
  export default {
    name: 'ui-button', // set block name
    props: ['size', 'look', 'type', 'icon'],
  }
</script>

<template>
  <button :class="b({ size, look })" :type="type">
    <span :class="b('text', { look })">
      <i v-if="icon" :class="b('icon', { icon })"> 👍 </i>
      <slot></slot>
    </span>
  </button>
</template>

Using ui-button block in App.vue:

<script>
  import Button from 'components/UI/Button.vue';

  export default {
    components: {
      'ui-button': Button
    },
  }
</script>

<template>
  <div class="example">
    <ui-button type="button" class="mix-any-class" size="large" look="primary" icon="emoji"> I am BEM button! </ui-button>
  </div>
</template>

Will be compile to:

<div class="example">
 <button class="mix-any-class ui-button ui-button--size-large ui-button--look-primary" type="button">
    <span class="ui-button__text ui-button__text--look-primary">
    <i class="ui-button__icon ui-button__icon--icon-emoji">👍 </i>
      I am BEM button!
    </span>
  </button>
</div>

Installation

• from npm:

npm i --save vue-bem-cn / yarn add vue-bem-cn

And install with Vue.use() in your main.js:

import vueBemCn from 'vue-bem-cn';

Vue.use(vueBemCn, {/* Your config, not required. See below */});

new Vue({...});

• from CDN:

<script src="https://unpkg.com/vue/dist/vue.min.js"></script>
<script src="https://unpkg.com/vue-bem-cn/dist/vue-bem-cn.umd.min.js"></script>
<script>
  Vue.use(vueBemCn, {/* Your config, not required. See below */});

  new Vue({...});
</script>

Usage

For class name generation, enough to call b() method with v-bind:class or use :class in your template. The Block name will be receive from name field of component or block field:

<script>
  export default {
    name: 'ui-button',
  }
</script>

<template>
  <div :class="b()"> DIV tag will receive 'ui-button' class name </div>
</template>

More examples in API section

After component initialization (created lifecycle hook), every component, that has string in name or block fields recive b() method. Also, you can call this.b() method in your component, if you need it.

Q: What if I don't want to use name field for Block name? And what is block field ?

If you want, you can use block field instead of name, but keep in mind, block prefer then name:

<script>
export default {
  name: 'ui-button',
  block: 'bem-button', // prefer then `name: 'ui-button'`
}
</script>

<template>
  <div :class="b()"> DIV tag will receive 'bem-button' class name </div>
</template>

Q: I will want use another delimiters for BEM entities. And still I need namespances.

No problem. You can set your settings object with Vue.use() as second argument:

  import Vue from 'vue';
  import vueBemCn from 'vue-bem-cn';

  // default delimiters settings
  const bemConfig = {
    delimiters: {
      ns: '', // namespace
      el: '__', // element delimeter
      mod: '--', // modifier delimeter
      modVal: '-', // value delimeter for modifier
    }
  }

  Vue.use(vueBemCn, bemConfig);

  new Vue({...});

Q: I will want use another name for b method.

Just change methodName option in config:

  import Vue from 'vue';
  import vueBemCn from 'vue-bem-cn';

  const bemConfig = {
    methodName: 'bem',
  }

  Vue.use(vueBemCn, bemConfig);

  new Vue({...});

Q: What about converting camelCase to kebab-case?

Check hyphenate option:

  import Vue from 'vue';
  import vueBemCn from 'vue-bem-cn';

  const bemConfig = {
    hyphenate: true,
  }

  Vue.use(vueBemCn, bemConfig);

  new Vue({...});

API

Block

Generate block name.

<script>
  export default {
    name: 'ui-button',
  }
</script>

<template>
  <div :class="b()"> DIV tag will receive 'ui-button' class name </div>
</template>

Modifier of Block

Generate modifier of block name.

<script>
  export default {
    name: 'ui-button',
  }
</script>

<template>
  <div :class="b({ size: 'large' })"> DIV tag will receive 'ui-button ui-button--size-large' class name </div>
</template>

Element of Block

Generate element of block name.

<script>
  export default {
    name: 'ui-button',
  }
</script>

<template>
  <div :class="b('text')"> DIV tag will receive 'ui-button__text' </div>
</template>

Modifier of Element

Generate modifier of element name.

<script>
  export default {
    name: 'ui-button',
  }
</script>

<template>
  <div :class="b('text', { look: 'primary' })"> DIV tag will receive 'ui-button__text ui-button__text--look-primary' class name </div>
</template>

Mixins

Mix class names to block/element.

• with vue-bem-cn in your component:

<script>
  export default {
    name: 'ui-button',
  }
</script>

<template>
  <div>
    <div :class="b(false, 'block-mixin')"> DIV tag will receive 'ui-button block-mixin' class name </div>
    <div :class="b('text', 'element-mixin')"> DIV tag will receive 'ui-button__text element-mixin' class name </div>
  </div>
</template>

• with Vue class attribute in parent component:

<script>
  import Button from 'components/UI/Button.vue';

  export  default {
    name: 'form',
    components: {
      'ui-button': Button
    },
  }
</script>

<template>
  <form :class="b()">
    <ui-button :class="b('button')"> ui-button root tag will receive 'form__button ui-button' class name </ui-button>
  </form>
</template>

Default settings

{
  hyphenate: false,
  methodName: 'b',
  delimiters: {
    ns: '',
    el: '__',
    mod: '--',
    modVal: '-'
  }
}

• hyphenate: boolean - hyphenation the resulting class name

// { hyphenate: true }

b({ hasFocus: true }) // block--has-focus

• methodName: string - name of the method for generating the class name

// { methodName: 'bem' }

b('elem') // [Vue warn]: Property or method "b" is not defined...
bem('elem') // block__elem

• delimiters: Object<string> - delimiters for BEM entities

// { delimiters: { ns: 'b-', modVal: '_'} }

b({ mod: 'val' }) // b-block b-block--mod_val