Sencha TextBox onkeypress Event Backspace KeyCode Does Not Work

Question

I have a textbox with onkeypress event. when user pressed backspace I need do some action but i could not catch backspace keycode value.

        var charCode = (evt.which) ? evt.which : event.keyCode
         if (charCode > 31 && (  charCode !=46 &&  (charCode < 48  || charCode > 57))   )
         {
            return false;
         }
else
{

    if(charCode===8)
    {
        alert('Gg');

    }

    var recentChar = String.fromCharCode(evt.which);
    var enteredtext=txtID.value+recentChar;
    if(parseFloat(enteredtext)>NewMobile.globals.activeFolioTotal)
    {

        return false;

    }

   var txtboxes = document.getElementsByClassName('clspaytype');
   var Totalprice=Ext.getCmp('spFolioPay').getHtml();

   Ext.getCmp('spFolioPay').setHtml( parseFloat( Totalprice)- parseFloat(enteredtext));



}

textbox :

 <input id="txtpt{payid}" onkeypress="return NewMobile.app.PaymentPriceControl(event,this)" class="clspaytype" type="text" style=" margin-left:10px; float:right ; width:100px" /> 

Answer 1

Changed onkeypress event to onkeydown and i get backspace now.