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hiding the link buttons when user leaves the text box

I have a text box and two link buttons on my web page. When I put some value on the text box, based on that value and also as soon as I leave the textbox. I want to hide or make the link button invisible.
<asp:textBox id="textBox1" runat="server">
<asp:linkButton id="link1" runat="server">
<asp:linkButton id="link2" runar="server">
when the user enter value "X" in the textbox, I want to hide Link1 and Link2 otherwise I want Link1 and Link2 to be visible.
here is my code and it is not working:
function HidePick(selectObj) {
if (selectObj.value.toUpperCase() == "D9") {
document.getElementById("LINK1").style.display = 'none';
}
}
<td><asp:TextBox ID="TXTTest1" runat="server" CssClass="cssTest" Width="30" onmouseout="javascript:HidePick(this);"
With error message:
"JavaScript runtime error: Unable to get property 'style' of undefined
or null reference

For that kind of DOM manipulation, it is easy with jQuery.
JS Fiddle - https://jsfiddle.net/p8pm6r5r
<asp:TextBox ID="textBox1" runat="server" />
<asp:LinkButton ID="link1" runat="server" Text="Button1" />
<asp:LinkButton ID="link2" runat="server" Text="Button2" />
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.2.4/jquery.min.js"></script>
<script type="text/javascript">
$(function() {
$("#<%= textBox1.ClientID %>").blur(function () {
if ($(this).val() === "X") {
$("#<%= link1.ClientID %>").hide();
$("#<%= link2.ClientID %>").hide();
}
});
})
</script>

In asp.net the final render id may change on page, so on javascript you need to use the .ClientID of control... you code must be as:
document.getElementById("<%=link1.ClientID%>").style.display = 'none';
Related: Accessing control client name and not ID in ASP.NET

<asp:textBox id="textBox1" runat="server">
<asp:LinkButton ID="link1" runat="server" Text="Button1" />
<asp:LinkButton ID="link2" runat="server" Text="Button2" />
Assuming you don't want to use jQuery or any library;
At the end of your htmls in .aspx page add a script tag to bind the button to mouseleave or mouseout events. Just to make sure your textbox1's id is static (the way it is in your source), once your page is rendered on the browser check for your textbox1 and see if it has still the same id if not then copy that id and replace in the below event binder line of javascript code from textbox1 to (whatever_textbox1). Same step for your link ids too.
document.getElementById("textBox1").addEventListener("mouseout",HidePick,false);
function HidePick(e){
if (e.target.value.toUpperCase() == "D9")
document.getElementById("LINK1").style.display = 'none';
}

Set asp.net textbox value using javascript

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.

<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>

Try including the ClientIDMode property in your textbox
<asp:TextBox ID="txtFlag" runat="server" Visible="False"
ClientIDMode="Static"></asp:TextBox>

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>

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.

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

Creating a Button Click Event and Validating TextBoxes using Javascript

I am having so much trouble with this. I have looked everywhere so I hope someone can either explain to me how to do this or show me. Here's my problem:
I have a DataGrid filled with DataBound Items (ItemTemplate) which was created using ASP.Net.
My reason for the ItemTemplates over a regular DataBound field is to enable the Edit Mode of the DataGrid. In my ItemTemplates, I have labels to display the data and two option buttons (Edit/Delete). I've got the buttons working in the code behind (C#).
Edit places the DataGrid in Edit Mode. In the EditItemTemplates I've got DropDownLists, TextBoxes, and a Save button in place of the Edit button.
The Save button also works with the code I've written for it. All-in-all, the DataGrid works beautifully and displays everything neatly. However, there is one final job I want the Save button to do: I want it to check the TextBoxes and validate that the values entered match the criteria I have set (keep in mind that these are in EditItemTemplates).
I have Javascript already written that will check for validation. I want a modal window (that I have already set up) to display and I want the CSS of the TextBoxes in question to change.
I want to do this using Javascript but my problem is that I can't check for the Save button to create the Click event and I can't 'locate' the TextBoxes to validate them. Is there a way I can 'find' those elements while the DataGrid is in Edit Mode?
Here's a small bit of the code used to create the DataGrid if it helps:
<asp:DataGrid ID="dgCamsizer" CssClass="data" runat="server" AutoGenerateColumns="False"
GridLines="None" OnItemCommand="dgCamsizer_ItemCommand" ShowHeader="true">
<Columns>
<asp:TemplateColumn HeaderStyle-CssClass="infoHeaderDG">
<HeaderTemplate>
Operator</HeaderTemplate>
<ItemTemplate>
<asp:Label ID="Operator" Text='<%# DataBinder.Eval(Container.DataItem, "Operator") %>'
runat="server" /></ItemTemplate>
<EditItemTemplate>
<asp:TextBox ID="EditOper" Width="40px" Text='<%# DataBinder.Eval(Container.DataItem, "Operator") %>'
runat="server"></asp:TextBox></EditItemTemplate>
<HeaderStyle CssClass="infoHeaderDG"></HeaderStyle>
</asp:TemplateColumn>
<asp:TemplateColumn HeaderStyle-CssClass="infoHeaderDG">
<ItemTemplate>
<asp:Button ID="Edit" Text="Edit" CommandName="Edit" runat="server" /></ItemTemplate>
<EditItemTemplate>
<asp:Button ID="Save" Text="Save" CommandName="Save" runat="server" /></EditItemTemplate>
<HeaderStyle CssClass="infoHeaderDG"></HeaderStyle>
</asp:TemplateColumn>
</Columns>
</asp:DataGrid>
Perhaps I should re-phase my question: I managed to 'find' the TextBoxes thanks to Zetlen. I've also managed to get the values. Now... How do I use those values to test for validation?
Here is the code I used to get the values:
$("#<%=dgCamsizer.ClientID %> :text").each(function () {
alert($(this).val());
});

ASP.NET webforms are hard to work with in JavaScript, because the IDs of your HTML elements change during the page lifecycle! The input you're calling "EditOper" will get an HTML ID of something like "dgCamSizer_ctl102_EditOper". One thing you can do is collect these elements on pageload in a cache of DOM element references. I recommend using jQuery or a similar DOM querying library.
<script type="text/javascript">
$(document).ready(function() {
var $editorElms = {},
idSeparator = "_"; // the underscore is ASP.NET's default ID separator, but this can be changed if you wish with the IDSeparator property.
$('#dgCamSizer input').each(function() {
$editorElms[this.id.split('_').pop()] = $(this);
});
// now you can access every input using the $editorElms hash.
// e.g.
function someValidationRoutine() {
if (!$editorElms.EditOper.val()) {
someErrorDisplayer("EditOper must not be blank.");
return false;
}
}
})
</script>
And, again using jQuery, the Save button shouldn't be too tough to find.
var $saveButton = $('#dgCamSizer :submit[value=Save]');
So you can bind the event that way:
$saveButton.click(function(e) {
if (!someValidationRoutine()) {
e.preventDefault();
}
});
This is not the most high-performance solution--selectors of that complexity are always a bit slower. But it gets the job done without messing too much with the DataGrid.

So I managed to solve my own problems and answer my own question. I was able to get the id's of all of the TextBoxes and I even placed them into an array to be used for my validations. Here's what I used to do all of this:
var i = 0;
var data = [];
$("#<%=dgCamsizer.ClientID %> :text").each(function () {
data[i] = $(this).attr("id");
i++;
});

Populate a TextBox from a DropDownList selection ASP.NET/Javascript

I have a DDL and ASP.NET Textbox. I would like to populate the text box with the option I choose from the DDL. I need this to be instant and not use postbacks so it would seem JavaScript would be the obvious choice here. I have done quite a bit of searching but everything I have found seems to be for standard HTML (Selects and Inputs) and these do not appear to work with ASP objects:
<asp:DropDownList runat="server" ID="DDLSalesPerson" DataValueField="keyid" DataTextField="FullName" />
<asp:TextBox runat="server" id="txtSalesPerson" />
My DDL is populated from SQL in the code-behind page.
Can somebody assist with the appropriate code I should use? Thanks.

ASP.Net controls render as standard HTML elements on the browser. In script, you can get a reference to them by using the ClientID property of the ASP.Net control.
Put this in a script block in your aspx:
var ddl = document.getElementById('<%=DDLSalesPerson.ClientID %>');
var textBox = document.getElementById('<%= txtSalesPerson.ClientID%>');
Now you have references to the DOM objects for the select and input elements that the ASP.Net controls rendered and you can use the techniques you've already learned on the HTML elements.
Additional info
You need to add an onchange attribute to your DropDownList control as such:
<asp:DropDownList runat="server" ID="DDLSalesPerson" DataValueField="keyid" onchange="ddlChange();" DataTextField="FullName" />
and then put this script block in your aspx
<script type="text/javascript">
function ddlChange()
{
var ddl = document.getElementById('<%=DDLSalesPerson.ClientID %>');
var textBox = document.getElementById('<%= txtSalesPerson.ClientID%>');
textBox.value = ddl.options[ddl.selectedIndex].text;
}
</script>
As you change the dropdown list, you'll see the textbox update. Tested in IE and Chrome.

Since you've pointed out that you're a JavaScript beginner, may i suggest you use an updatepanel control. An updatepanel allows you to execute server code without refreshing the page. Simply place the dropdownList and the textbox in the same updatepanel or in two separate updatepanels and write the code for the textbox to update based on the dropdownlist selection. Make sure to set the dropdownlist to do autopostback.
The asp markup is as follows:
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:DropDownList ID="ddlList" runat="server"
AutoPostBack="True">
<asp:ListItem>-select-</asp:ListItem>
<asp:ListItem>option 1</asp:ListItem>
<asp:ListItem>option 2</asp:ListItem>
</asp:DropDownList>
<asp:TextBox ID="txtTextBox" runat="server" />
</ContentTemplate>
</asp:UpdatePanel>
The codebehind in vb is as follows:
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If ddlList.Text <> "-select-" then
txtTextBox.Text = ddlList.text
End If
End Sub

If you're new to JavaScript, use the jQuery library (simply provide references to the CDN-hosted jQUery files at google.com) and then you can use the following code:
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.5/jquery.min.js"></script>
<script language="javascript" type="text/javascript">
$("#DDLSalesPerson").change(function () {
$("#txtSalesPerson").val($(this).val());
});
</script>

How can I defer loading UpdatePanel content until after the page renders?

Old hand at ASP.NET, new to the UpdatePanel. I have a reporting page which executes a fairly length SQL query... takes about 10 seconds right now. What I would like to do is have my page fully render, with some placeholder text (Loading...) and then have the UpdatePanel kick off the actual time-consuming reporting process and render the report when it's done.
So... my theory is to use RegisterStartupScript() to kick this off and drop the string from GetPostBackEventReference() to trigger the UpdatePanel update. Some problems crop up:
1) Can I actually use GetPostBackEventReference w/ the UpdatePanel or do I need to trigger it some other way? Use this method on a button inside the Update Panel?
2) What event gets triggered when the postback reference is the UpdatePanel? It's not clear to me. I've got to call my databinding code somewhere! Again, maybe I need to use a button inside?

I had to do something very similar recently, here's how i did it (right or wrong):
The trick is a "Hidden Async Postback Trigger".
<asp:UpdatePanel ID="upFacebookImage" runat="server">
<ContentTemplate>
<!-- Your updatepanel content -->
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="hiddenAsyncTrigger" EventName="Click" />
</Triggers>
</asp:UpdatePanel>
<asp:Button ID="hiddenAsyncTrigger" runat="server" Text="AsyncUpdate" style="display:none;" />
Then from JavaScript, whenever you want to trigger the async postback, you do this:
__doPostBack('<%= hiddenAsyncTrigger.ClientID %>', 'OnClick');
In my example, i needed to trigger an async postback from a particular JS event. But you could attach it to doc ready.
I seem to remember trying #Marko Ivanovski's way, but for some reason it didn't work. I think you need to specify a "postback-able" control (ie a button) to trigger the postback.
HTH.

Updating this with my solution, I pieced together mostly from the first answer above.
I need my page to load, then then start loading content for my update panel. The panel calls some webservices and we don't want the whole page to crash in the event that the remote server doesn't respond. We don't want the wait either.
My HTML:
<asp:UpdatePanel ID="udpCheckout" runat="server" UpdateMode="Always">
<ContentTemplate>
<asp:Image ID="imgSpinner" runat="server" Visible="true" ImageUrl="~/images/ajax-loader.gif" />
<br />
<asp:Label ID="lblWait" runat="server" Visible="true" Text="Please wait..."></asp:Label>
<asp:Button ID="hiddenAsyncTrigger" runat="server" Text="AsyncUpdate" style="display:none;" />
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="hiddenAsyncTrigger" EventName="Click" />
</Triggers>
</asp:UpdatePanel>
My Code behind snippets:
In page_load:
ScriptManager.RegisterStartupScript(Me.Page, Me.Page.GetType, "LoadUpdate", GetPostBackEventReference(hiddenAsyncTrigger, String.Empty), True)
And the button handler:
Sub LoadUpdatePanels(ByVal o As Object, ByVal e As EventArgs) Handles hiddenAsyncTrigger.Click
System.Threading.Thread.Sleep(5000) 'wait 5 seconds so I can see the page change
imgSpinner.Visible = False
lblWait.Text = "Content is now loaded."
'udpCheckout.Update()
End Sub
This was my test to see if I could get it working. Now to replace all of this with the real code!

Try something like this (not tested).
Set the UpdateMode of the UpdatePanel to Conditional.
Add this to your <head> section:
<script type="text/javascript">
window.onload = __doPostBack('UpdatePanel1', ''); // Replace UpdatePanel1 with the ID of your UpdatePanel
</script>

Simplifying RPM1984's very helpful earlier answer (thanks ;)) and showing some tweaks & a little more of the surrounding detail that I found necessary:
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:UpdatePanel ID="upFacebookImage" runat="server">
<ContentTemplate>
<asp:PlaceHolder runat="server" ID="PlaceHolderMediaPrompts" />
<asp:Button ID="hiddenAsyncTrigger" runat="server" Text="AsyncUpdate" OnClick="WasPage_Load" style="display:none;" />
</ContentTemplate>
</asp:UpdatePanel>
Note:
The hidden button's vital OnClick= parameter, this is what specifies the server function to call!
No trigger clause or triggers in the Update-panel, I am using the child controls which are automatically triggers - specifically the button Click event.
And to trigger it from client-side Javascript you can use:
document.getElementById("hiddenAsyncTrigger").click‌​();
However, I found it necessary to prevent this being called on subsequent page loads (as it caused unnecessary page load looping & consequent flicker). See the neat little IsPostBack() check below :)
e.g. To invoke this after page load (as per the original question), I just added a call to invoke the above line of code as the onload-parameter to the main Body-tag thus:
<body onload="DoPostLoad();">
...
<script type="text/javascript">
function DoPostLoad()
{
if ( IsPostBack() != true ) // ***This is NEW and ESSENTIAL! ***
document.getElementById("hiddenAsyncTrigger").click();
}
function IsPostBack() { // Ref. https://stackoverflow.com/questions/26978112/execute-javascript-only-on-page-load-not-postback-sharepoint
var ret = '<%= Page.IsPostBack%>' == 'True';
return ret;
}
. . .
</script>
</body>