vue的自定义指令

1. 点击元素之外触发函数

   <template>
     <div v-clickoutside="clickItemOut"></div>
   </template>
   
   const clickoutside = {
     bind (el, binding, vnode) {
       function documentHandler (e) {
         if (el.contains(e.target)) {
           return false
         }
         if (binding.expression) {
           binding.value(e)
         }
       }
       el.__vueClickOutside__ = documentHandler
       document.addEventListener('click', documentHandler)
     },
     unbind (el, binding) {
       document.removeEventListener('click', el.__vueClickOutside__)
       delete el.__vueClickOutside__
     }
   }
   
   组件中声明自定义指令（全局也可以，改写成全局各式就好了）
   directives: { clickoutside }
   
   methods: {
       clickItemOut (e) {
         // 点击元素之外触发函数
       }