Invalid Expression term 'string' when i assign variable in client side

Question

How can i assign variable in aspx page?

See i have tried

 <div>
      <asp:TextBox ID="UsernameTextBox" Text="xxx" runat="server"></asp:TextBox>
      <%= string ss=  UsernameTextBox.Text.ToString() %>
      <asp:Button ID="btnLogin" runat="server" 
           OnClientClick="LoginPopup( <%=  UsernameTextBox.Text  %>);  return false;"
           CssClass="login-button" Text="xxx">
      </asp:Button>
 </div>

I have assigned usernametextbox value in string

 <%= string ss =  UsernameTextBox.Text.ToString() %>

But it's showing error like : Invalid Expression term 'string'

Why i can't do that? Is it possible?

But if i remove the "string ss= " then it's <%= UsernameTextBox.Text.ToString() %> working good.

I can't assign the values to a string variable. Why?

Is a bug in .net?or any wrong syntax format?

this answer may help stackoverflow.com/questions/1499261/… — Nogard
– Nogard, Commented Dec 12, 2013 at 13:24

Habib · Accepted Answer · 2013-12-12 13:24:03Z

7

If you have to assign a value to variable then you should use normal script tag like:

<% string ss = UsernameTextBox.Text.ToString(); %>

Later if you want to render that value then you can do:

<%= ss %>

You may see: Embedded Code and Inline Server Tags

answered Dec 12, 2013 at 13:24

Habib

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2 Comments

Ramesh Rajendran Over a year ago

Gooood. Now i get the value

<asp:Button ID="btnLogin" runat="server" OnClientClick="LoginPopup( '<% ss  %>');  return false;"                 CssClass="login-button" Text="xxx"></asp:Button>

.but it's not working

Habib Over a year ago

@RameshRajendran, it should be <%=, not just <%

user447356 · Accepted Answer · 2013-12-12 13:42:32Z

0

In addition to be rather non-so-elegant Spaghetti code, your logic is also flawed and you will always get the initial textbox value, not the current value at the time of clicking.

To kill two birds in one shot and have both better code style and working code, first change the markup to be just this:

<asp:Button ID="btnLogin" runat="server" OnClientClick="return LoginPopup();" CssClass="login-button" Text="xxx"></asp:Button>

Now have this in your JS function:

function LoginPopup() {
    var name = document.getElementById("<%=UsernameTextBox.ClientID%>").value;
    //...code using the name here...
    return false;
}

You read the value at the time of clicking now.

answered Dec 12, 2013 at 13:42

user447356

1 Comment

user447356 Over a year ago

So don't use it. I just show more elegant way for the sake of those who will want to use it. Also, see what happens if the user name contains a single quote. (hint: your code will break, this code will not)

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