Check Checkbox from code behind asp.net

Question

I want to change my Checkbox states when I write any thing in a textbox so I did

<asp:CheckBox ID="chkIceChest" Text="Ice Chest" runat="server" />
<asp:TextBox ID="txtIceChest" Text="$ cost" runat="server" CssClass="moch-cost" AutoPostBack="true" OnTextChanged="CalculateStand" />

and

protected void CalculateStand(object s, EventArgs e)
{
     double total = 0, cost = 0;
     if (txtIceChest.Text.Length > 0 && txtIceChest.Text != "$ cost")
     {
         cost = Convert.ToDouble(txtIceChest.Text.Replace("$", ""));
         total += cost;
         if (cost > 0) chkIceChest.Checked = true;
     }
}

but it is not working !!!! why ?

I really think you should look at using client side script for this. Do you really want to post back to the server every time the textbox value changes just to update something in the UI? Madness my friend, madness. — Rich Andrews
– Rich Andrews, Commented Jun 12, 2013 at 16:27
@RichAndrews, I agreed with you in so much that I went ahead and provided the OP that solution. I've been maintaining some old projects here at work lately and somebody used an UpdatePanel to do something like this. :( — Mike Perrenoud
– Mike Perrenoud, Commented Jun 12, 2013 at 16:39

Mike Perrenoud · Accepted Answer · 2013-06-12 16:42:04Z

4

How about a client-side approach? I mean, to be perfectly honest, UI operations like this are best fit there. First, you'll need to change your markup a little:

<asp:CheckBox ID="chkIceChest"
              ClientIDMode="Static"
              Text="Ice
              Chest" runat="server" />
<asp:TextBox ID="txtIceChest"
             ClientIDMode="Static"
             Text="$ cost"
             runat="server"
             CssClass="moch-cost" />

and now you'll need a little JavaScript, just throw this on your ASPX page:

<script type="text/javascript">
    $('#txtIceChest').blur(function() {
        var total = 0;
        var cost = 0;
        var val = $('#txtIceChest').val();
        var chkIceChest = $('#chkIceChest');

        if (val && val.length > 0 && val != "$ cost") {
            cost = val.replace('$', '');
            total += cost;
            if (cost > 0) {
                chkIceChest.attr('checked', 'checked');
            }
        }
    });
</script>

but this approach would happen in the browser and real-time for you. Also, the value would get posted back just as if the user had checked the check box.

edited Jun 12, 2013 at 16:42

answered Jun 12, 2013 at 16:35

Mike Perrenoud

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8 Comments

kartal Over a year ago

So this function will work on textchange or only when page is loading ?

Mike Perrenoud Over a year ago

@kartal, currently it works on blur. Like your current code did. However, if you want it on text changed then just use change instead of blur.

kartal Over a year ago

It is not working for me . did you miss anything because I am not good in javascript

Mike Perrenoud Over a year ago

@kartal: you need to download and link the jQuery JavaScript file for this code to work.

kartal Over a year ago

I already have it <script type="text/javascript" src="code.jquery.com/jquery-1.8.3.min.js"></script>

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