Detailed example of how JS calculates age based on birthday

This article mainly introduces the JS method of calculating age based on birthdays, involving javascript related skills in operating time. It is very simple and practical. Friends in need can refer to the following examples

Learn how to calculate age based on birthday in JS. 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+&#39;-&#39;+brithd+"_ddd");
      age = (todayYear*1-birthdayYear*1);
    }
    else
    {
      age = (todayYear*1-birthdayYear*1)-1;
    }
  }
 }
 return age*1;
 }
 else
 {
 return -1;
 }
}

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