功能：element-ui 的 el-date-picker 请求发送 默认当前时间区间 (前两天-至今)
调用：
this.dialogParams.StartDate = this.getTime(-2) //前两天
this.dialogParams.EndDate = this.getTime(0) //当天
方法如下：
getTime(day) {
const today = new Date()
const targetday = today.getTime() + 1000 * 60 * 60 * 24 * day
today.setTime(targetday) //关键代码
const tYear = today.getFullYear()
let tMonth = today.getMonth()
let tDate = today.getDate()
tMonth = this.doHandleMonth(tMonth + 1)
tDate = this.doHandleMonth(tDate)
return tYear + '-' + tMonth + '-' + tDate
},
doHandleMonth(month) {
let m = month
if (month.toString().length === 1) {
m = '0' + month
}
return m
},
