Ajax does not call Spring Boot driver

Hi, I have trouble calling a controller using ajax, what I want to do is go to another page using ajax.

        function validar(){
            var codigo= $('#codigo').val();
            $.ajax({
                type : "GET",
                url : "/host/validar",
                data: {
                    "codigo" : codigo
                },
                success: function(result) {
                   alert("success");
                },
                error : function(e) {
                   alert("error");
                }
            });
        }

the html with thymeleaf

<div class="x_content">
<section class="text-center">
    <h5><span>Ingrese codigo</span></h5>
    <form id="formValidar">
        <div>
            <input type="text" class="form-control" placeholder="codigo" required="" id="codigo" name="codigo" />
        </div>
        <br>
        <div>
            <button class="btn btn-dark" type="button" onclick="validar()">Validar</button>
        </div>
    </form>
 </section>
</div>

and in my controller

@RequestMapping(value = "/validar", method = RequestMethod.GET)
public @ResponseBody String validar(
        @RequestParam("codigo") String codigo){
    System.out.println("entro sdgsdgdsg");
    System.out.println("codigo: "+codigo);
    Usuario usuario = usuarioService.buscarPorCodigo(codigo);
    if (usuario == null){
       return "pagina-validar";
    }
    return "nueva-pagina";
}

I have added the @Controller annotation in the class, and I have another example almost the same in another class and if it works, but it does not even enter the method.