小程序 把时间里的时分 转换成数字相减后得差

页面

<template>
  <view class="pages" v-if="viewPage">
    <u-form :model="form" :label-style="{'font-size':'26rpx'}">
      <u-form-item label="场地名称" label-width="200">
        <view>{{formItem.title}}</view>
      </u-form-item>
      <u-form-item label="预订时间" label-width="200">
        {{make_time}} {{make_start}}-{{make_end}}
      </u-form-item>
      <u-form-item label="单价">
        <view>{{formItem.price}}</view>
      </u-form-item>
      <u-form-item label="使用时间" label-width="200">
        {{getDuration()}} 
      </u-form-item>
      <u-form-item label="合计" label-width="200">
        <div>{{  (formItem.price *  formItem.duration || 0).toFixed(2) }}</div>
      </u-form-item>
      <u-form-item label="联系人" label-width="200">
        <u-input v-model="formItem.user_name" />
      </u-form-item>
      <u-form-item label="联系电话" label-width="200">
        <u-input v-model="formItem.user_mobile" maxlength="11" />
      </u-form-item>
      <u-form-item label="预计人数" label-width="200">
        <u-input v-model="formItem.number" />
      </u-form-item>
    </u-form>

    <view class="btn_bb">
      <view class="btn_text">
        <view class="fukuan">实付金额 ¥ 0 （入驻企业预订限时免费）</view>
        <view class="confirm" @click="confirmFn">确定</view>
      </view>
    </view>
  </view>
</template>

js逻辑

   methods: {
    getDuration () {
      let make_start=this.make_start.split(':')
      let make_ends=this.make_end.split(':')
      let hour=Number(make_ends[0])-Number(make_start[0])
      let minute=(Number(make_ends[1])-Number(make_start[1]))/60
      this.formItem.duration= hour+minute
      return this.formItem.duration
    },
    
  }