get year of birth from age javascript code example

Example 1: javascript get age

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;
}

Example 2: javascript work out age from date of birth

// To calculate age:
var year_born = prompt("Please enter your date of birth:", "Type here");
var d = new Date();
var n = d.getFullYear();
function getAge(birthYear){
	var currentDate = new Date();
    var currentYear = currentDate.getFullYear();
    age = currentYear - birthYear;
    return age;
}
calculatedAge = getAge(year_born);
alert("Hello, " + "you are " + calculatedAge + " years old!");

Example 3: javascript get day of year from date

//Month -> 0= Jan, 11=Dec | myDate = 6 Dec 2019 10:45
var myDate = new Date(2019, 11, 06, 10, 45);
var dayInYear = Math.floor((myDate - new Date(myDate.getFullYear(), 0, 0)) / (1000 * 60 * 60 * 24));