Set variable on jQuery selector

Question

I saw some posts on the subject, but it did not help.

the problem is this:

CSS:

.spanClass{
 display: none;
}

HTML:

<input type="text" name="nome" id="nome">
<span class="spanClass"></span>

jQuery:

        $("#nome").on("keypress", function(){
            mask($(this), maskName);
        });

        function mask(o,f){
            v_obj = o;
            v_fun = f;
            setTimeout("execMask()",1)
        }

    function execMask(){
        var id = v_obj.attr('id'); // aqui eu pego o id 
        console.log(typeof(id)); // result: string
        v_obj.val(v_fun(v_obj.val(),id)); // aqui eu passo o valor do campo do meu input e o id dele.
    }


//nesta função eu recebo o regex, alvo(valor do input), uma msg, e o id(Sim já verifiquei no console, todos esses valores chegam até minha função alertMsg.

function alertMsg(regex,alvo,msg,id){
    if(regex.test(alvo)){
        $("#"+id).text(msg).fadeIn(); // esse comando não funciona.
    } else {
        $('#'+id).text("").fadeOut(); // esse comando não funciona.
    }
}

Can anyone tell me why I can’t put a variable in the jQuery selector?

NOTE: the last command does not show any error in the console, it simply does not run, if I manually put the id it works.

OBJECTIVE: When placing NOT allowed characters, displays an msg below the input.

Answer 1

SOLUTION:

CSS:

.spanClass{
 display: none;
}

HTML:

<input type="text" name="nome" id="nome">
<span id="nomeSpan" class="spanClass"></span>

jQuery:

function mask(o,f){
    v_obj = o;
    v_fun = f;
    setTimeout("execMask()",1)
}

function execMask(){
    var id = v_obj.attr('id');
    v_obj.val(v_fun(v_obj.val(),id));
}

function replaceName(){
    $("#nome").on("keypress", function(){
        mask($(this), maskName);
    });
}

function alertMsg(regex,alvo,msg,id){
    if(regex.test(alvo)){
        $("#"+id+"Span").text(msg).fadeIn();
    } else {
        $('#'+id+"Span").text("").fadeOut();
    }
}

TOPIC ERROR ABOVE:

I was taking the id of the input itself and wanting to display a message in SPAN with it, I just changed this line on html, <span id="nomeSpan" class="spanClass"></span>, and this line on jQuery $("#"+id+"Span").text(msg).fadeIn();, so I can display the message below the input that had the false if condition returned.