asp.net value of C# var in JS

Question

I have a simple JS pop up "are you sure..." window, along with a dropdownlist and asp:button. What I want when I click the button is to get this message:

"Are you sure you want to perform <%= ACTION %>?"

where ACTION is a string coming from dropdownlist.SelectedItem.Text.

The following does not seem to work:

OnClientClick="return confirm('Are you sure you want to perform <%= ACTION %>? );

It actually just prints the <%= ACTION %> instead of the value.

I have also tried:

function testMe() {
    return confirm('Are you sure you want to perform ' + document.getElementById('<%= hfAction.ClientID %>').value + '?');
}

OnClientClick="testMe();"

But the above causes postback regardless of clicking cancel or OK.

Which is the correct usage?

how you have defined ACTION in your C# code

Habib
– Habib

2012-07-19 12:43:52 +00:00
Commented Jul 19, 2012 at 12:43 — Habib
– Habib, Commented Jul 19, 2012 at 12:43
yes its a simple string.

user1468537
– user1468537

2012-07-19 12:46:19 +00:00
Commented Jul 19, 2012 at 12:46 — user1468537
– user1468537, Commented Jul 19, 2012 at 12:46

Alex Mendez · Accepted Answer · 2012-07-19 13:48:38Z

2

Try this:

<asp:DropDownList runat="server" ID="ACTION">
    <asp:ListItem>Action 1</asp:ListItem>
    <asp:ListItem>Action 2</asp:ListItem>
</asp:DropDownList>

<script type="text/javascript">
    function ExecuteConfirm() {
        var ddlId = '<%= ACTION.UniqueID %>';
        var action = $("#" + ddlId + " option:selected").text();
        return confirm('Are you sure you want to perform ' + action + ' ?');
    }
</script>

<asp:Button runat="server" Text="Button" OnClientClick="return ExecuteConfirm();" />

answered Jul 19, 2012 at 13:48

Alex Mendez

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3 Comments

user1468537 Over a year ago

Microsoft JScript runtime error: The value of the property '$' is null or undefined, not a Function object

Alex Mendez Over a year ago

I used jquery on my sample code. You can use "var action = document.getElementById(ddlId).value;" instead of the like that contains the "var action = $..."

user1468537 Over a year ago

Ok i was just missing the import in the header. Works fine now. Thanks :)

Paul Fleming · Accepted Answer · 2012-07-19 13:54:47Z

2

You can't use server tags inside of server control declarations. Set the OnClientClick script in the code behind when initialising the object.

mybutton.OnClientClick 
    = string.format("return confirm('Are you sure you want to perform {0}?');", ACTION);

edited Jul 19, 2012 at 13:54

answered Jul 19, 2012 at 12:51

Paul Fleming

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1 Comment

Paul Fleming Over a year ago

In what sense? Same issue? Error?

Paul Aldred-Bann · Accepted Answer · 2012-07-19 13:56:15Z

1

Sorry, my last answer was complete garbage (didn't think before posting). What about this (you're almost right)?

function testMe() {
    var val = document.getElementById('<%= hfAction.ClientID %>').value;
    return confirm('Are you sure you want to perform ' + val + '?');
}

OnClientClick="return testMe();"

You just missed the return on the OnClientClick.

answered Jul 19, 2012 at 13:56

Paul Aldred-Bann

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2 Comments

user1468537 Over a year ago

Almost there. The problem I'm having is that it is not picking up the new value of hfAction.value after I select another item on the DDL. If I do a postback only then it picks up the value. I set it like so:

protected void ddlActions_SelectedIndexChanged(object sender, EventArgs e)     {         hfAction.Value = ddlActions.SelectedItem.Text;     }

Paul Aldred-Bann Over a year ago

Can you not just query the DDL instead of hfAction then? So document.getElementById('ddlActions.ClientID').value?

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