var date = new Date();
var curr_date = (date.getMonth() + 1) + '/' + date.getDate() + '/' + date.getFullYear();
var u_birthsday = 10/10/2001;//как пример
if(val != '' && curr_date > u_birthsday) {
//script
}
let now = new Date(),
birthday = new Date('10/10/2001')
if (now > birthday) {
// ...
}