Check user Age using Jquery(datepicker) & JSP

Question

Needing to implement a javascript function where calculates user age, informs an alert if it is under 18.Use Jquery library along with JSP,where datepicker is automatically loaded given a framework Annotation.

Excerpt from the Code JSP

<n:panelGridBootstrap >
  <t:property name="dtnascimento"  />
</n:panelGridBootstrap> 

Javasscript

var esteAno = new Date().getFullYear();
$("input[name='dtnascimento']").datepicker({
  dateFormat: 'dd-mm-yy',
  onSelect: function(date) {
    var ano = date.split('-')[2]; // ano aqui
    var idade = esteAno - ano;

   if(idade<18){
   alert("Menor de Idade");
}  

Answer 1

Your logic is correct. I suggest you join changeYear: true, to the datepicker and add } and }); missing from your code, to close the onSelect, but also the object and method invoked in .datepicker({.

As a matter of typing I suggest using Number to do the math with numbers: Number(date.split('-')[2]).

var esteAno = new Date().getFullYear();
$("input[name='dtnascimento']").datepicker({
  dateFormat: 'dd-mm-yy',
  changeYear: true,
  onSelect: function(date) {
    var ano = Number(date.split('-')[2]);
    var idade = esteAno - ano;

    if (idade < 18) {
      alert("Menor de Idade");
    }
  }
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://code.jquery.com/ui/1.12.0/jquery-ui.js"></script>
<link href="https://code.jquery.com/ui/1.12.0/themes/smoothness/jquery-ui.css" rel="stylesheet" />

<input name="dtnascimento" />