求一javascript， button1点后另外一个button可用！
<asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="申请" Width="72px" />
<asp:Button ID="Button3" runat="server" Text="确认" OnClick="Button3_Click" Width="80px" disabled="true" />
要求：页面打开的时候button3为disabled="true",点button1后，button3为可用disabled="false"

[解决办法]