After Effects Expressions - Calculate age given the birth date in the format MM/DD/YYYY

Question

So I need to to calculate someone’s age based on the current date vs a string of date. I’m having trouble figuring out the expression to calculate the age.

I have to calculate someone’s age from a string that is the birth date, e.g 12/22/1989 based on the current date.

On one text layer, the birthdate(e.g 12/22/1989) will be inputted and on the other layer, the age should be outputted.

TIA!

So what I have now is this:

var birthDateString = thisComp.layer("Birth Date").text.sourceText;
function dateToCurrentFormat(dateString) {
    var parts = dateString.split(/[/]/);
    var month = Number(parts[0]) - 1; // months are 0-based
    var day = Number(parts[1]);
    var year = Number(parts[2]);
    return new Date(year, month, day);
}

function difference(date1, date2, interval) {
    var second = 1000,
    minute = second * 60,
    hour = minute * 60,
    day = hour * 24,
    week = day * 7;
date1 = new Date(date1);
date2 = new Date(date2);
var timediff = date2 - date1;
if (isNaN(timediff)) return NaN;
switch (interval) {
  case "years":
    return date2.getFullYear() - date1.getFullYear();
  case "months":
    return (
(date2.getFullYear() * 12 + date2.getMonth()) -
(date1.getFullYear() * 12 + date1.getMonth())
);
  case "weeks":
    return Math.floor(timediff / week);
  case "days":
    return Math.floor(timediff / day);
  case "hours":
    return Math.floor(timediff / hour);
  case "minutes":
    return Math.floor(timediff / minute);
  case "seconds":
    return Math.floor(timediff / second);
    default:
    return undefined;
}
}

var birthDate = dateToCurrentFormat(birthDateString);

var age = difference(birthDate, new Date(), "years");

var ageString = age + " years old";
ageString;

Each time I’m getting an error for different things. First, it was “dateToCurrentFormat is not defined” then, ” difference is not defined” and then “object of type found where a Number, Array, or property is needed” for the variable age.

What am I doing wrong here? Maybe I’m doing it more difficult than it should be, if there’s an easier way to get to the result please let me know!

I've also tried the following:

var dob = thisComp.layer("Birth Date").text.sourceText;
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--;
}

age;

But I'm getting the result NaN. I'm guessing I need to do something with parse or integer in this code? But not sure how to go about it.

I'm not familiar with After Effects expressions, but since it looks like you have access to Date objects, there should be plenty of questions covering this, e.g. [Get difference between 2 dates in JavaScript?](https://stackoverflow.com/questions/3224834/get-difference-between-2-dates-in-javascript) — DBS, Jan 05 '23 at 11:14

score 1 · Answer 1 · answered Jan 05 '23 at 11:25

You can do it using simple approach. Here is one.

function getCurrentAge(userDate){
  let dob = new Date(userDate); // creating string date into date object
  let monthDifference = Date.now() - dob.getTime(); // calculate months difference till current date time
  let ageInDateFormat = new Date(monthDifference);  // converting the calculated difference in date format 
  let year = ageInDateFormat.getUTCFullYear();  // extracting year from date 
  let age = Math.abs(year - 1970);  //calculating the age of user
  return age;
}

console.log(getCurrentAge('1995-06-12'));

After Effects Expressions - Calculate age given the birth date in the format MM/DD/YYYY

1 Answers1