input输入框只能是数字

$('.dianhua').bind('input propertychange', function() {
            var val = $('.dianhua').val().trim();
            $('.dianhua').val(val);
            if(val){
                var phone = '';
                var regPos = /^\d+$/;
                for(var i=0;i<val.length;i++){
                    if(regPos.test(val[i])){
                        phone = phone+''+val[i];
                    }else{
                        $('.dianhua').val(phone);
                    }
                }

            }else{
                $('.dianhua').val('');
            }
        });