bootstrap-vue/src/directives/hover/hover.js

BootstrapVue, with more than 85 custom components, over 45 plugins, several custom directives, and over 300 icons, provides one of the most comprehensive implementations of Bootstrap v4 components and grid system for Vue.js. With extensive and automated W

// v-b-hover directive
import { isBrowser } from '../../utils/env'
import { EVENT_OPTIONS_NO_CAPTURE, eventOnOff } from '../../utils/events'
import { isFunction } from '../../utils/inspect'

// --- Constants ---

const PROP = '__BV_hover_handler__'
const MOUSEENTER = 'mouseenter'
const MOUSELEAVE = 'mouseleave'

// --- Utility methods ---

const createListener = handler => {
  const listener = evt => {
    handler(evt.type === MOUSEENTER, evt)
  }
  listener.fn = handler
  return listener
}

const updateListeners = (on, el, listener) => {
  eventOnOff(on, el, MOUSEENTER, listener, EVENT_OPTIONS_NO_CAPTURE)
  eventOnOff(on, el, MOUSELEAVE, listener, EVENT_OPTIONS_NO_CAPTURE)
}

// --- Directive bind/unbind/update handler ---

const directive = (el, { value: handler = null }) => {
  if (isBrowser) {
    const listener = el[PROP]
    const hasListener = isFunction(listener)
    const handlerChanged = !(hasListener && listener.fn === handler)
    if (hasListener && handlerChanged) {
      updateListeners(false, el, listener)
      delete el[PROP]
    }
    if (isFunction(handler) && handlerChanged) {
      el[PROP] = createListener(handler)
      updateListeners(true, el, el[PROP])
    }
  }
}

// VBHover directive

export const VBHover = {
  bind: directive,
  componentUpdated: directive,
  unbind(el) {
    directive(el, { value: null })
  }
}