JS method to calculate age based on birthday_javascript skills

The example in this article describes the JS method of calculating age based on birthday. Share it with everyone for your reference. The specific implementation method is as follows:

function parseDate(str){
 if(str.match(/^\d{4}[\-\/\s+]\d{1,2}[\-\/\s+]\d{1,2}$/)){
  return new Date(str.replace(/[\-\/\s+]/i,'/'));
 }
 else if(str.match(/^\d{8}$/)){
  return new Date(str.substring(0,4)+'/'+str.substring(4,6)+'/'+str.substring(6));
 }
 else{
  return ('时间转换发生错误！');
 }
}
function GetAgeByBrithday(birthday){
 var age=-1;
 var today=new Date();
 var todayYear=today.getFullYear();
 var todayMonth=today.getMonth()+1;
 var todayDay=today.getDate();
 var birthday=parseDate(birthday);
 if(parseDate(birthday)!='时间转换发生错误！')
 {
 birthdayYear=birthday.getFullYear();
 birthdayMonth=birthday.getMonth();
 birthdayDay=birthday.getDate();
 if(todayYear-birthdayYear<0)
 {
  alert("出生日期选择错误!");
 }
 else
 {
  if(todayMonth*1-birthdayMonth*1<0)
  {
    age = (todayYear*1-birthdayYear*1)-1;
  }
  else
  {
    if(todayDay-birthdayDay>=0)
    {//alert(thisDay+'-'+brithd+"_ddd");
      age = (todayYear*1-birthdayYear*1);
    }
    else
    {
      age = (todayYear*1-birthdayYear*1)-1;
    }
  }
 }
 return age*1;
 }
 else
 {
 return -1;
 }
}

I hope this article will be helpful to everyone’s JavaScript programming design.