React 根据条件自动计算

1.输入框

            <Item {...formItemProps} label="留房日期">
              {getFieldDecorator('date', {
                rules: [{ required: true, message: '请选择留房日期!' }],
              })
              (<RangePicker style={{ width: '66%', marginRight: '4%' }} value={date} onChange={this.setTotalPrice} />)
              }
            </Item>
            <Item {...formItemProps} label="单价">
              {getFieldDecorator('unitPrice', {
                rules: [{ required: true, message: '请输入单价' }],
              })(<Input placeholder="请输入" value={unitPrice} onChange={this.setTotalPrice} />)} 
            </Item>
            <Item {...formItemProps} label="间数">
              {getFieldDecorator('roomNum')(<InputNumber value={roomNum} onChange={this.setTotalPrice} />)}
            </Item>

2.计算函数

  /**
   * 计算总价：保留几位小数
   * 总价=单价[unitPrice]*留芳天数[date]*间数[roomNum]
   * 留房天数=留房天数：（留房结束时间-留房开始时间）+1
   */
  setTotalPrice = (e) => {
    const {
      form:{
        setFieldsValue
      }
    } = this.props
    let { 
      unitPrice,
      date,
      roomNum,
    } = this.state

    if(e.target){
      if(e.target.id === 'unitPrice'){
        unitPrice = e.target.value
      }else{
        roomNum = e.target.value
      }
      this.setState({
        [e.target.id]: e.target.value
      })
    }else if(typeof(e) === 'number'){
      roomNum = e
      this.setState({
        roomNum: e
      })
    }else{
      const dateData = [e[0].format('YYYY-MM-DD'), e[1].format('YYYY-MM-DD')]
      date = dateData
      this.setState({
        date: dateData
      })
    }

    if(unitPrice === '' || unitPrice === null || date === [] || date === null || roomNum === '' || roomNum === null) {
      this.setState({totalPrice: ''})
      setFieldsValue({ totalPrice: '' })
      return
    }

    const roomNumInt = parseInt(roomNum, 10)
    const unitPriceFloat = parseFloat(unitPrice)
    const leaveDayNum = getAllDate(date[0], date[1]).length
    const totalPrices = (roomNumInt*unitPriceFloat*leaveDayNum).toFixed(2).toString()
    this.setState({ totalPrice: totalPrices})
    setFieldsValue({ totalPrice: totalPrices })
  }