使用javascript设置asp.net文本框值

Question

I want to set the value of a asp.net textbox using javascript

My JS Code is:

document.getElementById('<%=txtFlag.ClientID %>').value = "Track";

My textbox is:

<asp:TextBox ID="txtFlag" runat="server" Visible="False"></asp:TextBox>

But it gives me an error document.getElementById(...)' is null or not an object

I dont understand what is wrong.

Please help.

Answer 1

<asp:TextBox ID="txtFlag" runat="server" Visible="False"></asp:TextBox>

Setting visible=false will cause this textbox to not appear in the rendered page. Remove this, and add display:none;

<asp:TextBox ID="txtFlag" runat="server" style="display:none;"></asp:TextBox>

Answer 2

Try including the ClientIDMode property in your textbox

<asp:TextBox ID="txtFlag" runat="server" Visible="False" 
                                     ClientIDMode="Static"></asp:TextBox>

Answer 3

You are calling javascript before complete document load . Please write your javascript code on document.ready function like this

 <script src="http://code.jquery.com/jquery-1.9.1.js"></script>
    <script type="text/javascript">

        $(document).ready(function() {
        document.getElementById('<%=txtFlag.ClientID %>').value = "Track";
        });

    </script>

And second thing is that use display none in place of visible false or use hidden field control

<asp:TextBox ID="txtFlag" runat="server" style="display:none;"></asp:TextBox>

Answer 4

document.getElementById('txtFlag').value='Track'

尝试这个

Answer 5

Solution 1:

Make that textbox as visible=true and try,

When you make a control as visible false, that control will not be loaded in client side and as you knew javascript will be executed on client side itself.

Solution 2:

Add this javascript at the end of the page.