Calculate age using Java script

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Hello i am trying to calculate the age of a person as per value given in text box. Here is my code:

JavaScript

function calculateage(birthday) 
        {

        var re=/^(0[1-9]|1[012])[- /.](0[1-9]|[12][0-9]|3[01])[- /.](19|20)\d\d+$/;
        if(birthday.value !='')
        {
        if(re.test(birthday.value))
        {
        birthdayDate=new Date(birthday.value);
        dateNow=new Date();
        var years=dateNow.getFullYear() - birthdayDate.getFullYear();
        var month=dateNow.getMonth() - birthdayDate.getMonth();
        var days=dateNow.getDate() - birthdayDate.getDate();
        if(isNaN(years)){
        document.getElementById('lblage').innerHTML= '';
        document.getElementById('lblerror').innerHTML='Input data is Incorrect';
        return false;
        }
        else
        {
        document.getElementById('lblerror').innerHTML='';
        if(month<0||(month==0 && days < 0))
        {
        years.parseInt(years)-1;
        document.getElementById('lblage').innerHTML=years+'years';

        }
        else
        {
        document.getElementById('lblage').innerHTML=years+ 'years';
        }
        }
        }
        else
        {
        document.getElementById('lblerror').innerHTML='Date must be in mm/dd/yyyy format';
        return false;
        }
        }
        }

Here is my Html Code

ASP.NET

<body>
    <form id="form1" runat="server">
    <div>
    Date of Birth:<asp:TextBox ID="txt1" onblur="calculateage(this)" runat="server">(mm/dd/yyyy)
</asp:TextBox>
    <span style="color:Red">
    <asp:Label ID="lblerror" runat="server"></asp:Label>
    </span>
    <br />
    Age:     :<span id="lblage"></span>
    </div>
    </form>
</body>

But when i leave the textbox after input date, It does not give anything.
Please help

Posted 11-Aug-12 18:00pm

_Raj sinha

Updated 24-Dec-20 1:50am

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2 solutions

Solution 2

function calculate_age()
{
var birth_date=new Date()(document.getElementByID("birth_date").value);
var birth_date_day= birth_date.getDate();
var birth_date_month=birth_date.getMonth();
var birth_date_year=birth_date.getFullYear();

var today_date=new Date();
var today_day=today_date.getDate();
var today_month=today_date.getMonth();
var today_year=today_date.getFullYear();

var calculated_age=0;

if (today_month> birth_date_month) calculated_age=today_year-birth_date_year;
else if(today_month == birth_date_month)
{
if (today_day>= birth_date_day) calculated_age=today_year-birth_date_year;
else calculated_age= today_year-birth_date_year-1;
}
else calculated_age=today_year-birth_date_year-1;

var calculated_age=today_year-birth_date_year;
var output_value=calculated_age;
document.getElementById("calculated_age").innerHTML=calculated_age;
}

Posted 24-Dec-20 1:39am

Member 15029554

Updated 24-Dec-20 1:46am

v3

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_Amy · Accepted Answer · 2012-08-11T18:15:00

Solution 1

Hi,
Try this,
Javascript:

JavaScript

function getAge(dateString) {
    var today = new Date();
    var birthDate = new Date(Date.parse(dateString.value, "MM/dd/yyyy"));
    var age = today.getFullYear() - birthDate.getFullYear();
    var m = today.getMonth() - birthDate.getMonth();
    if (m < 0 || (m === 0 && today.getDate() < birthDate.getDate())) {
        age--;
    }
    document.getElementById("lblage").innerHTML = age;
}
}

HTML:

ASP.NET

<form id="form1"  runat="server">
    <div>
        Date of Birth:<asp:TextBox runat="server" ID="txt1" onblur="getAge(this)">MM/dd/yyyy
        </asp:TextBox>
        <span style="color: Red">
            <asp:label id="lblerror" runat="server"></asp:label>
        </span>
        <br />
        Age: :<span id="lblage"></span>
    </div>
    </form>

--Amit

Posted 11-Aug-12 18:15pm

_Amy

Updated 11-Aug-12 19:16pm

v2

Comments

_Raj sinha 12-Aug-12 0:37am

Hi Amit, I have tried your given code but its not working.

Gee Varghese 25-Oct-13 22:37pm

Hello, he you are getting date in MM/dd/yyyy .
How i it possible to get date in dd/MM/yyyy

_Amy 12-Aug-12 0:52am

Try the updated answer. Now it'll work out.

_Raj sinha 12-Aug-12 1:26am

hii Amit, thanx for replying now your given code is working.But I want to calculate month and day along with age. can you help?

_Amy 12-Aug-12 1:30am

There only you can calculate that. Read the better article from the net. If you'll try yourself then only you can enhance your skills and problem solving ability. All the best. :)

_Raj sinha 12-Aug-12 1:31am

Thnx Amit