Checking whether inputs are empty with Javascript

Question

I have the code below that creates three fields in HTML these fields go through the checks below with Javascript, however, the part that should check if the person typed something does not work, I am doing it the right way?

function checadatas(){
    var form_ins = document.acess;
    console.log(form_ins);
    var data1 = new Date(form_ins.inp.value);
    var data2 = new Date(form_ins.fip.value);
    if (!data1 || !data2){
      return false;
    }
    if (data1 > data2){
      alert("Data não pode ser maior que a data final");
      return false;
    } else {
      return true;
    }
    if(document.acess.inp.value == null){
            alert("Digite uma data!");
            return(false);
        } else if(document.acess.fip.value == null){
            alert("Digite uma data!");
            return(false);
        } else if(document.acess.ver.value == null){
            alert("Digite uma data!");
            return(false);
        } else {
          return true;
    }
}

<form method="POST" action="#" onSubmit="return checadatas()" name="acess">
<br><br>
<a a class="arib">Data de inicio da verificação: </a><input type="date" name="inp"/>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
<a a class="arib">Data de fim da verificação: </a><input type="date" name="fip"/>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
<br><br><br>
<a a class="arib">Data ser realizada a verificação: </a><input type="date" name="ver"/>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
<br><br><br>
       <button class="css_btn_class" type="submit" name="Enviar">Inserir ativo</button>
</form>

Answer 1

Are you checking in document.acess.inp.value after the method has already finished, "How so?" -Simple, in the if before the check if it is equal to null, you run a return it doesn’t matter if data1 > ou < a data2, the call to return ends the method call. To correct, I believe it is necessary to place the last if first of all in the way.

Answer 2

Two problems:

These two returns is preventing the rest of the function from being executed. In fact what I left commented is not necessary, because you want to do only negative validation:

if (data1 > data2){
  alert("Data não pode ser maior que a data final");
  return false;
} else {
  // return true;
}

The other is the comparisons with null:

document.acess.inp.value == null

The values of the fields are not null when they are empty. You can check this way:

!document.acess.inp.value // se for vazio, é false

Another point is that you don’t need to return true at the end of the function. If the function does not return any false, nothing will prevent the submit proceed.

Code with corrections:

function checadatas(){
    var form_ins = document.acess;
    console.log(form_ins);
    var data1 = new Date(form_ins.inp.value);
    var data2 = new Date(form_ins.fip.value);
    if (!data1 || !data2){
      return false;
    }
    if (data1 > data2){
      alert("Data não pode ser maior que a data final");
      return false;
//    } else {
//      return true;
    }
    if(!document.acess.inp.value){
            alert("Digite uma data!");
            return false;
     } else if(!document.acess.fip.value){
         alert("Digite uma data!");
         return false;
     } else if(!document.acess.ver.value){
         alert("Digite uma data!");
         return false;
     }
}