Activating event from checkbox

Question

I tried to do the checkbox to change a input of hidden for text, but I don’t know what I’m missing.

function myFunction() {

    const selecionado = document.querySelector("#quant");
    var checkBox = document.getElementById("ch_quant");

    var input = document.getElementById("quant").type = 'hidden';


    if (checkBox.checked == true){
       document.getElementById("quant").type = 'text'
    }
    else {
        document.getElementById("quant").type = 'hidden'
    }
}

<div class="form-group col-md-12">
  <label for="nome">Marque P/ Informar Estoque</label>
  <input type="checkbox" id="ch_quant" name="ch_quant" required>
  <input type="hidden" id="quant" name="quant">
</div>

Answer 1

First of all you should call the function you created when there is change in the checkbox with the onchange="myFunction(this)".

Second, with the this you pass the function parameter itself input (<input type="checkbox" id="ch_quant" name="ch_quant" onchange="myFunction(this)" required>).

After that just check if it’s marked or not, just like you’ve already done.

function myFunction(checkbox) {

  if (checkbox.checked)
    document.getElementById("quant").type = 'text'    
  else 
    document.getElementById("quant").type = 'hidden'
    
}

<div class="form-group col-md-12">
  <label for="nome">Marque P/ Informar Estoque</label>
  <input type="checkbox" id="ch_quant" name="ch_quant" onchange="myFunction(this)" required>
  <input type="hidden" id="quant" name="quant">
</div>