//匹配yyyyMMddHHmmss格式的日期，例如：20200317112000
var pattern = /(\d{4})(\d{2})(\d{2})(\d{2})(\d{2})(\d{2})/;
//将时间格式化成 yyyy-MM-dd HH:mm:ss
var formatDateStr = dateStr.replace(pattern, '$1/$2/$3 $4:$5:$6');
//将时间转成Date
var formatDate = new Date(formatDateStr);