elementui的时间选择器按周选择时展示具体日期范围

HTML代码：

<el-date-picker
               v-model="week"
               @change="changeTime"
               :picker-options="{firstDayOfWeek: 1}"
               type="week"
               :format="startTimeStamp + ' 至 ' + endTimeStamp"
               placeholder="选择周">
</el-date-picker>

使用 :picker-options="{firstDayOfWeek: 1}"改变周起始日，默认是7
js代码：

changeTime(val) {
                if(val) {
                    let timeStamp = val.getTime(); //标准时间转为时间戳，毫秒级别
                    this.startTimeStamp = this.timeFun(timeStamp - 24 * 60 * 60 * 1000); //开始时间
                    this.endTimeStamp = this.timeFun(timeStamp + (24 * 60 * 60 * 1000) * 5); //结束时间
                    console.log(this.startTimeStamp, this.endTimeStamp)
                    this.searchData.firstDate = new Date(this.startTimeStamp + ' 00:00:00').getTime() //+ ' 00:00:00' //new Date(this.startTimeStamp + ' 00:00:00').getTime() / 1000
                    this.searchData.lastDay = new Date(this.endTimeStamp + ' 23:59:59').getTime() //+ ' 23:59:59' //new Date(this.endTimeStamp + ' 23:59:59').getTime() / 1000
                }else{
                    this.searchData.lastDay = undefined
                    this.searchData.lastDay = undefined
                }
            },

            //时间戳转为yy-mm-dd hh:mm:ss
            timeFun(unixtimestamp) {
                var unixtimestamp = new Date(unixtimestamp);
                var year = 1900 + unixtimestamp.getYear();
                var month = "0" + (unixtimestamp.getMonth() + 1);
                var date = "0" + unixtimestamp.getDate();
                // var hour = "0" + unixtimestamp.getHours();
                // var minute = "0" + unixtimestamp.getMinutes();
                // var second = "0" + unixtimestamp.getSeconds();
                return year + "-" + month.substring(month.length - 2, month.length) + "-" + date.substring(date.length - 2, date
                        .length)
                    //     +
                    //" " + hour.substring(hour.length - 2, hour.length) + ":" +
                    //minute.substring(minute.length - 2, minute.length) + ":" +
                    //second.substring(second.length - 2, second.length);
            },