Control the CSS style of the control in the CS file.

First, in the aspx foreground file:

<SCRIPT type = "text/JavaScript">
Function Change (s)
{

Switch (s)
{
Case "fixed term ":
Document. getelementbyid ("Panel1"). style. Display = "Block ";
Document. getelementbyid ("panel2"). style. Display = "NONE ";
Document. getelementbyid ("panel3"). style. Display = "NONE ";<p>_ ICMs</p> <br>
<br>
<br>
<br>
<br>
<br>
Document. getelementbyid ("panel2"). style. Display = "Block ";
Document. getelementbyid ("panel3"). style. Display = "NONE ";
Document. getelementbyid ("panel4"). style. Display = "NONE ";
Document. getelementbyid ("panel5"). style. Display = "NONE ";
Break;
Case "part-time ":
Document. getelementbyid ("Panel1"). style. Display = "NONE ";
Document. getelementbyid ("panel2"). style. Display = "NONE ";
Document. getelementbyid ("panel3"). style. Display = "Block ";
Document. getelementbyid ("panel4"). style. Display = "NONE ";
Document. getelementbyid ("panel5"). style. Display = "NONE ";
Break;
Case "employment agreement ":
Document. getelementbyid ("Panel1"). style. Display = "NONE ";
Document. getelementbyid ("panel2"). style. Display = "NONE ";
Document. getelementbyid ("panel3"). style. Display = "NONE ";
Document. getelementbyid ("panel4"). style. Display = "Block ";
Document. getelementbyid ("panel5"). style. Display = "NONE ";
Break;
Case "labor dispatch ":
Document. getelementbyid ("Panel1"). style. Display = "NONE ";
Document. getelementbyid ("panel2"). style. Display = "NONE ";
Document. getelementbyid ("panel3"). style. Display = "NONE ";
Document. getelementbyid ("panel4"). style. Display = "NONE ";
Document. getelementbyid ("panel5"). style. Display = "Block ";
Break;
Default:
Break;
}
}
</SCRIPT>

<Table>
<Tr>
<TD Height = "30" style = "width: 214px"> contract type </TD>
<TD> & nbsp; <asp: dropdownlist id = "ddlcontract" runat = "server" width = "131px" onchange = "Change (this. Value)">
<Asp: listitem value = "fixed term"> fixed term </ASP: listitem>
<Asp: listitem value = "complete a task"> complete a task </ASP: listitem>
<Asp: listitem value = "part-time"> part-time </ASP: listitem>
<Asp: listitem value = "employment agreement"> Employment Agreement </ASP: listitem>
<Asp: listitem value = "labor dispatch"> labor dispatch </ASP: listitem>
</ASP: dropdownlist>
</TD>
<TD> & nbsp; </TD>
</Tr>
</Table>

<Asp: Panel id = "Panel1" runat = "server" style = "display: none" Height = "30px" width = "125px">
<Asp: Panel id = "panel2" runat = "server" style = "display: none" Height = "30px" width = "125px">
<Asp: Panel id = "panel3" runat = "server" style = "display: none" Height = "30px" width = "125px">
<Asp: Panel id = "panel4" runat = "server" style = "display: none" Height = "30px" width = "125px">
<Asp: Panel id = "panel5" runat = "server" style = "display: none" Height = "30px" width = "125px">

--------------------------------------------
If you want to write the CSS style of the panel in the. CS file, you need to write it like this.
. Aspx. CS

This. panel3.style. Add ("display", "Block ");

--------------------------------------------

If it is written as this. panel3.visible = true; then it does not work for the front-end style = "display: none" control.