javascript – How to disallow numbers in a textbox?

Question:

Hi guys, I'm trying to do a validation but I still haven't been successful. I want to make a function that doesn't let me enter numbers in a textbox .

Here's an example of how I currently do it.

 $(document).ready(function () {
    $('#nome_contacto').change(function validar() {
        var textoValida = $('#nome_contacto').val();

        if (textoValida == "1" || textoValida == "2" || textoValida == "3" || textoValida == "4" || textoValida == "5" || textoValida == "6" || textoValida == "7" || textoValida == "8" || textoValida == "9") {
            window.alert("Só letras");
        }
    });
});

Answer:

You can do this using a Regular Expression. Look:

  $('#nome_contacto').on('input', function(e) {
    if(/[0-9]/g.test(this.value)){
      alert("Apenas letras");  
    }
  });

In this case, the expression was /[0-9]/g which checks for the existence of numbers, which can be replaced by \d .

test here

$('#nome_contacto').on('input', function() {
  if (/[0-9]/g.test(this.value)) {
    alert("Apenas letras");
  }
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<textarea id="nome_contacto" ></textarea>

But if you really want to block numbers from entering you can check the keyCode . The complete list of these is here .

The keyCodes of the numbers range from 48 to 57, so I checked 47 > keyCode < 57 .

$('#nome_contacto').keypress(function(e) {
  var keyCode = (e.keyCode ? e.keyCode : e.which); // Variar a chamada do keyCode de acordo com o ambiente.
  if (keyCode > 47 && keyCode < 58) {
    e.preventDefault();
  }
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<textarea id="nome_contacto"></textarea>

I used the .preventDefault() method to block the input.

Here's an alternative if you just want numbers…

Due to the ambiguity of the question, I made this option:

$('#nome_contacto').keypress(function(e) {
  var keyCode = (e.keyCode ? e.keyCode : e.which);
  if (!(keyCode > 47 && keyCode < 58)) {
    e.preventDefault();
  }
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<textarea id="nome_contacto"></textarea>

In this case, just deny the condition of the previous option.