function testaNumeroDigitacao(e) {  

    var key = window.event ? window.event.keyCode : e.which ;
    
    ////Tratamento para Firefox
    //if(key<48 && !window.event || key == 8 || key == 9) 
    //   return true;
    
    //EXCESSÕES (backspace del)
    if (key == 0 || key == 8)
        return true;
    
    if(key < 48 || key > 57)
    {			
		return false;
	}
    return true;    
}