全局定义

# main.js
Vue.directive('drop', {  
  inserted: function (el) {
    let userUA = navigator.userAgent;
    if (userUA.indexOf('iPhone') > -1){  
       el.onblur = function(){              
            setTimeout(function(){
              var scrollHeight = document.documentElement.scrollTop || document.body.scrollTop || 0;
              window.scrollTo(0, Math.max(scrollHeight - 1, 0)); 
            },100)  
            console.log(userUA)
        }
    }
  }
})

# 页面.vue
<input v-drop />