i want to make something with javascript

Question

I want to make a promote box to ask user their age...
and return value with their birth year..
how can I make it..
please tell me...

Answer 1

var a = prompt("Please enter your age");
var d = new Date();
d=d.getFullYear();
document.write("Your birth year is "+eval("d-a"));

Answer 2

thanks a lot..👌✌