Age from Date of Birth using JQuery

Question

I need to calculate if someone is over 18 from their date of birth using JQuery.

var curr = new Date();
curr.setFullYear(curr.getFullYear() - 18);

var dob = Date.parse($(this).text());

if((curr-dob)<0)
{
    $(this).text("Under 18");
}
else
{
    $(this).text(" Over 18");
}

There must be some easier functions to use to compare dates rather than using the setFullYear and getFullYear methods.

Note: My actual reason for wanting to find a new method is length of the code. I have to fit this code into a database field that is limited to 250 chars. Changing the database is not something that can happen quickly or easily.

Answer 1

You could use the Date object. This will return the milliseconds between the two dates. There are 31556952000 milliseconds in a year.

function dateDiff(var now, var dob) { return now.getTime() - dob.getTime(); }

Answer 2

$(this).text(((new Date().getFullYear()-Date.parts($(this).text()))>=18)?"Over 18":"Under 18");

Better? :D

Answer 3

You can remove the separate variable for DOB and collapse the if statement. The below code comes in at 165 characters:

var check = new Date();
check.setFullYear(check.getFullYear() - 18);
$(this).text((new Date("3/6/2009").getTime() - check.getTime() < 0)?"Under 18":"Over 18");

This will still keep the logic needed to deal with leap-years.

Answer 4

You might find the open source Datejs library to be helpful. Specifically the the addYears function.

var dob = Date.parse($(this).text());
if (dob.addYears(18) < Date.today())
{
    $(this).text("Under 18");
}
else
{
    $(this).text(" Over 18");
}

In a more terse fashion:

$(this).text(
    Date.parse($(this).text()).addYears(18) < Date.today() ?
    "Under 18" :
    " Over 18"
)

Answer 5

Date.prototype.age=function(at){
    var value = new Date(this.getTime());
    var age = at.getFullYear() - value.getFullYear();
    value = value.setFullYear(at.getFullYear());
    if (at < value) --age;
    return age;
};

var dob = new Date(Date.parse($(this).text()));

if(dob.age(new Date()) < 18)
{
    $(this).text("Under 18");
}
else
{
    $(this).text(" Over 18");
}