Try this..
<script>
function getAge() {
var dateString = document.getElementById("date").value;
if(dateString !="")
{
var today = new Date();
var birthDate = new Date(dateString);
var age = today.getFullYear() - birthDate.getFullYear();
var m = today.getMonth() - birthDate.getMonth();
var da = today.getDate() - birthDate.getDate();
if (m < 0 || (m === 0 && today.getDate() < birthDate.getDate())) {
age--;
}
if(m<0){
m +=12;
}
if(da<0){
da +=30;
}
if(age < 18 || age > 100)
{
alert("Age "+age+" is restrict");
} else {
alert("Age "+age+" is allowed");
}
} else {
alert("please provide your date of birth");
}
}
</script>
<input type="text" id="date" value="1987/08/31" onblur="getAge()">
8
solved I need to restrict age for below 18 years age from the current date in Php