Question

I have a variable in javascript:

var activeSearchButton = document.getElementById('<%=btnSearch.ClientID %>');

I want to set it like this:

<asp:TextBox ID="WFTo" runat="server" onchange="activeSearchButton = document.getElementById('<%=btnWFSearch.ClientID %>');"></asp:TextBox>

When I am trying to use the varible in javascript function, it is null. And the source shows:

onchange="activeSearchButton = document.getElementById('<%=btnSearch.ClientID %>');"

I noticed ‘& lt;’ instead of “<“. Is this the reason of my problem? Why does this happen? Or maybe there is another reason?

Thank you very much.

Answer 1

Just create a function in <script /> section

function setActiveSearchButton()
{
    activeSearchButton = document.getElementById('<%=btnSearch.ClientID %>');
}

and use

<asp:TextBox ID="WFTo" runat="server" onchange="setActiveSearchButton()"></asp:TextBox>

EDIT:

As it turns out, you cannot use <%= .. %> for server side controls. You’ll have to resolve to using a regular html input like this

<input type="text" onchange="setActiveSearchButton('<%= btnSearch.ClientID %>')" />

and

function setActiveSearchButton(buttonId)
{
    activeSearchButton = document.getElementById(buttonId);
}

or leave the <asp:TextBox /> as it is and on Page_Load do

 protected void Page_Load(object sender, EventArgs e)
 {
     WFTo.Attributes.Add("onchange", "setActiveSearchButton('" + btnSearch.ClientID +"')");
 }