ifui/packages/mixins/bem.js

/**
 * bem helper
 * b() // 'button'
 * b('text') // 'button__text'
 * b({ disabled }) // 'button button--disabled'
 * b('text', { disabled }) // 'button__text button__text--disabled'
 * b(['disabled', 'primary']) // 'button button--disabled button--primary'
 */

 const ELEMENT = '__'
 const MODS = '--'

 const join = (name, el, symbol) => el ? name + symbol + el : name

 const prefix = (name, mods) => {
   if (typeof mods == 'string') {
     return join(name, mods, MODS)
   }

   if (Array.isArray(mods)) {
     return mods.map(item => prefix(name, item))
   }

   const ret = {}
   Object.keys(mods).forEach(key => {
     ret[name + MODS + key] = mods[key]
   })
   return ret
 }

 export default {
   methods: {
     b(el, mods) {
       const {name} = this.$options

       if (el && typeof el !== 'string') {
         mods = el
         el = ''
       }
       el = join(name, el, ELEMENT)
       return mods ? [el, prefix(el, mods)] : el
     }
   }
 }