# how to calculate age from date of birth in javascript?

how to calculate age from date of birth in javascript – 2 ways to calculate age in Javascript first is Calculate age from date of birth to current date and Calculate the age between the given two dates.

## how to calculate age from date of birth in javascript

Question : What is the formula for calculating age with a variable date of birth? here you can Calculate Age JavaScript Code and Explanation. First I define a variable called DOB to store a persons Date of Birth.

### How to calculate age in JavaScript with demo?

HTML Code
Calculate age from date of birth to current date

```<input type="date" id="txtDOB" />
<button id="btnCalculate"  onclick="fnCalculateAge();" >Calculate Age</button>
```

here simply you can easy to convert user input value into date object and get difference from current date;

``` function fnCalculateAge(){

var getDtLive = document.getElementById("txtDOB").value;
console.log(getDtLive);

var born_date = new Date(getDtLive);
console.log(" birthDate"+ born_date);

var diff_dt=Date.now() - born_date.getTime();

var  ageDate = new Date(diff_dt);
var total_calc_member_age=   Math.abs(ageDate.getUTCFullYear() - 1970);
}
```

### Calculate the age between given two date.

HTML code

```<input type="date" id="st_dt" />
<input type="date" id="end_dt" />
<button id="btnCalculate2"  onclick="allCalcAge();" >Calculate Age</button>
```

js code
here simply convert user input values into date object and get difference between two date.

``` function allCalcAge(){
var sdi = document.getElementById("st_dt").value;
var edi = document.getElementById("end_dt").value;

var sd = new Date(sdi);
var ed  = new Date(edi);

var diff_dt=ed - sd.getTime();

var  ageDate = new Date(diff_dt);
var total_calc_member_age=   Math.abs(ageDate.getUTCFullYear() - 1970);