Disable number input in a text input with js

Question

What I have to do is not permit to introduce number characters in a text input in a form, but I've to do it with javascript. Here's my HTML code:

<form id="formu">
<input type="text" id="num" />
</form>

And here's my JS code:

function numero(theEvent){

    var evento=theEvent||window.event;

        switch(evento.type){
            case 'keypress':
                if(document.getElementById("num").evento.keyCode>=48&&document.getElementById("num").evento.keyCode<=57){
                    return false;
                }
        }
    }

Answer 1

You can use the new pattern attrib HTML ,

<input type="text" id="num" pattern="[A-Za-z]" title="Only Alphabets">

Answer 2

function validateKeyStrokes(event) {
    var charCode = (event.which) ? event.which : event.keyCode;
    if (charCode > 31 && (charCode < 48 || charCode > 57)) {
        return false;
    }
    return true;
}


<form id="formu">
<input type="text" id="num"  onkeypress="return validateKeyStrokes(event)" />
</form>

Try this