JS函数：

function KeyCheckInt(events)
    {
        if (events.charCode == 0) return;//在FF下屏蔽退格、方向键等功能键，charCode在IE下为undefined非0
        var reTest = /^(48|49|50|51|52|53|54|55|56|57)?$/;
        e = events || window.event;
        if (e.charCode == 0) return;
        var code = e.keyCode || e.which;
        if (!(reTest.test(code)))
        {
            if (window.event)  //IE
                {   event.returnValue = false;   }
            else //Firefox                          
                {   events.preventDefault();  }
        }
     }

调用：

onKeyPress="KeyCheckInt(event);"

例如：

<asp:TextBox ID="txtTradeAmountFrom"
                        runat="server" CssClass="width-field-content-half" MaxLength="10" onKeyPress="KeyCheckInt(event);"></asp:TextBox>