使用vuetify picker和momentjs获取两次之间的差异

<template>
  <div>
    <v-date-picker v-model="startDate"></v-date-picker>
    <v-time-picker v-model="startTime"></v-time-picker>
    <v-date-picker v-model="endDate"></v-date-picker>
    <v-time-picker v-model="endTime"></v-time-picker>
    <button @click="calculateDiff">计算差异</button>
    <p>差异：{{ diff }}</p>
  </div>
</template>

<script>
import moment from 'moment';

export default {
  data() {
    return {
      startDate: null,
      startTime: null,
      endDate: null,
      endTime: null,
      diff: null
    };
  },
  methods: {
    calculateDiff() {
      const start = moment(`${this.startDate} ${this.startTime}`);
      const end = moment(`${this.endDate} ${this.endTime}`);
      this.diff = end.diff(start);
    }
  }
};
</script>