问vue.js中的无限循环警告

EN

Vue.directive 'datepicker',
  bind: () ->
    vm = this.vm
    key = this.expression
    datepicker = $(this.el).datepicker
      todayBtn: 'linked'
      language: 'de'
      daysOfWeekDisabled: '0'
      calendarWeeks: true
      todayHighlight: true
      toggleActive: true
      autoclose: true
    datepicker.on 'changeDate', (e) ->
      vm.$set key, e.date
  update: (val) ->
    $(this.el).datepicker 'setDate', val

You may have an infinite update loop for watcher with expression: date

vm.$set key, e.date