Calculate age given the birth date in the format YYYYMMDD

Question

How can I calculate an age in years, given a birth date of format YYYYMMDD? Is it possible using the Date() function?

I am looking for a better solution than the one I am using now:

var dob = '19800810';  var year = Number(dob.substr(0, 4));  var month = Number(dob.substr(4, 2)) - 1;  var day = Number(dob.substr(6, 2));  var today = new Date();  var age = today.getFullYear() - year;  if (today.getMonth() < month || (today.getMonth() == month && today.getDate() < day)) {    age--;  }  alert(age);

Answer 1

Try this.

function getAge(dateString) {     var today = new Date();     var birthDate = new Date(dateString);     var age = today.getFullYear() - birthDate.getFullYear();     var m = today.getMonth() - birthDate.getMonth();     if (m < 0 || (m === 0 && today.getDate() < birthDate.getDate())) {         age--;     }     return age; } 

I believe the only thing that looked crude on your code was the substr part.

Fiddle: http://jsfiddle.net/codeandcloud/n33RJ/

Answer 2

I would go for readability:

function _calculateAge(birthday) { // birthday is a date     var ageDifMs = Date.now() - birthday.getTime();     var ageDate = new Date(ageDifMs); // miliseconds from epoch     return Math.abs(ageDate.getUTCFullYear() - 1970); } 

Disclaimer: This also has precision issues, so this cannot be completely trusted either. It can be off by a few hours, on some years, or during daylight saving (depending on timezone).

Instead I would recommend using a library for this, if precision is very important. Also @Naveens post, is probably the most accurate, as it doesn't rely on the time of day.

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