Referencing ASP.NET element in JQuery - javascript

I don't seem able to simply reference my dropdownlist control by specifying id of the control in this case. Any one able to help?
<asp:Panel ID="PnlRepImp" runat="server">
<div class="module-row">
<table>
<tr>
<td>
<telerik:RadComboBox ID="SelectRole" runat="server" Width="250px" Height="150px"
EmptyMessage="Select a Company" OnClientSelectedIndexChanged="PageMethods.LoadUsers(this);" EnableLoadOnDemand="true" ShowMoreResultsBox="true"
EnableVirtualScrolling="true">
</telerik:RadComboBox>
</td>
</tr>
</table>
</div>
</asp:Panel>
Also would appreciate information on how I could learn to do this in all cases.

$('#<%= ControlYouWant.ClientID %>')
That should give you a jQuery instance of what you want.

you need to get the client id in your javascript like this
alert('<%= Control.ClientID %>');
var list=$('<%= "#"+ Control.ClientID %>');

You wouldn't be able to match the ASP.NET control using JQuery selector with ID "SelectRole" because the ID on the ClientID would be something like "ParentControlID_SelectRole". Sometimes you can use something like $("ParentControlID_SelectRole") to match it because you observe during development that that's the client-side ID "consistently" genereated by ASP.NET. I don't like this approach since sometimes you would re-arrange the controls heirarchy and your matching algorithm no longer works.
You can add a CssClass element to your ASP.NET control and set its value equal to the control ID. In this case, you would set CssClass="SelectRole" and then in JQuery, you can match with $(".SelectRole").
Or, you use JQuery wildcard (*) selector to match the element like the following:
var theCombobox = $("select[id*='SelectRole']"); //assumed to be <select> on client DOM

Related

Why the disabled button is not getting enabled using the jquery? [duplicate]

I'm trying make some stuff in jQuery using ASP.NET. But the ID from runat="server" is not the same as the id used in HTML.
I used to use this to get the ID from this situation:
$("#<%=txtTest.ClientID%>").val();
But in this case, it does not work. I'm clueless as to why.
Javascript
/* Modal */
function contatoModal() {
//alert("Test");
alert($("#<%=txtTest.ClientID%>").val());
}
HTML
< input runat="server" id="txtTest" value="test" />
Any tips?
<%= txtTest.ClientID %> should work but not in a separate javascript file where server side scripts do not execute. Another possibility is to use a class selector:
<input runat="server" id="txtTest" value="test" class="txtTest" />
and then:
var value = $('.txtTest').val();
In WebForm / HTML Page....
<asp:TextBox ID="txtUserName" runat="server" Class="form-control"></asp:TextBox>
In Jquery
var UserName = $("[id*=txtUserName]").val();
alert(UserName);
100% Sure its Working for me....
As others have mentioned, you can pass a class selector to jQuery, but that is a bit messy. I prefer to use the jQuery attribute ends with selector. Given that a generated ID is a flattened hierarchy of controls, you can use the "ends with" selector to find your element.
<input runat="server" id="txtText" />
When rendered, the generated ID becomes something like this (if within a masterpage's content place holder):
<input id="ctl00_contentplaceholder_txtText" />
To find this control:
$("input[id$='txtText']")
Take caution when using this within a repeater.
Try putting it into a variable name:
var txtTestID = '#' + '<%=txtTest.ClientID %>';
$(txtTestID).val();
I'm not sure if the <%= likes being inside double quotes. I've always had mixed behaviors when not using the single quote.
When using ASP.NET 4 and the ClientIDMode is set to “Predictable”, you can predict the ID based on hierarchy. Or set it set to “Static”, so asp.net wont mess it up.
ScottGu's article on it http://weblogs.asp.net/scottgu/archive/2010/03/30/cleaner-html-markup-with-asp-net-4-web-forms-client-ids-vs-2010-and-net-4-0-series.aspx
And this is extremely useful when using external JS file scenarios.
As Darin Dimitrov said in his answer:
<%= txtTest.ClientID %> should work but not in a separate javascript
file where server side scripts do not execute.
The solutions that I could find for those are:
<input runat="server" id="txtTest" value="test" class="txtTest" />
Use class instead of ID
Using class you can retrieve the value anywhere. This is one of the best solutions (usually the best)
var value = $('.txtTest').val();
Use ClientID code in the aspx
You can always call ClientID in the aspx, but if you are working with some kind of structure, this isn't the best solution. I like to use this method when I'm testing something.
var value = $('#<%=txtTest.ClientID%>').val();
You can also use ClientID in a external js file with a workaround. IT'S NOT PRETTY, use only if you really need it. I usually do this when I use Telerik.
In the aspx:
var id = <%=txtTest.ClientID%>;
In the js file:
var value = $('#'+id).val();
Use Control.ClientIDMode Property Static
so the HTML becomes
<input runat="server" id="txtTest" value="test" ClientIDMode="Static" />
and the js can call it as it is named of
var value = $('#txtTest').val();
The problem with this solution is that you need to be very careful to avoid duplicity on the ids of your page. Try never use Static mode in a controller.
As states MSDN:
The ClientID value is set to the value of the ID property. If the
control is a naming container, the control is used as the top of the
hierarchy of naming containers for any controls that it contains.
The link of shaans's answer is a awesome place to check extra information about ClientIDMode.
Cleaner HTML Markup with ASP.NET 4 Web Forms - Client IDs (VS 2010 and .NET 4.0 Series)
To avoid issues with rendered ID's, use a class instead. This won't change during rendering:
function contatoModal() {
//alert("Test");
alert($(".txtTest").val());
}
HTML:
< input runat="server" id="txtTest" value="test" class="txtText" />
Adding a css class to the input and then using this class in jQuery to getting the input element will solve the issue.

Write runat="server" in javascript string

All I want to do is write this string "runat='server'"; in javascript. and use that here:
var dropdown = "<td><asp:DropDownList ID='drpid' runat='server' DataSourceID='SqlDataSource1' DataValueField='Id' DataTextField='Text'></asp:DropDownList></td>"
error is this: SyntaxError: missing ) after argument list
ASP.NET is rendering the control inside your string definition.
The output of that <asp:DropDownList> contains newlines, double quotes, and references to javascript functions, so it will definitely make a mess of your javascript string.
Instead, let asp.net render the dropdown somewhere else (it can even be inside an invisible div) like this :
<div id="hiddenthingContainer" style="display:none;">
<asp:dropdownlist /> ... etc
</div>
Then, either use document.getElementById("hiddenthingContainer") or use jQuery or whatever dom library you prefer to get the element.
once you have it, it becomes a simple matter of getting the contents of the hidden container and presto, there's your string.
example using jQuery :
<div id="hiddenthingContainer" style="display:none">
<asp:DropDownList ID='drpid' runat='server' DataSourceID='SqlDataSource1' DataValueField='Id' DataTextField='Text'></asp:DropDownList>
</div>
<script type="text/javascript">
$(document).ready(function(){
var dropdown = $("#hiddenthingContainer").html()
});
</script>

How to find "a href" tag inside a List View in asp.net using jquery

I need to find anchor tag in side a <asp:ListView> using jquery.
Sample code is given below.
<asp:ListView ID="lstview" runat="server">
<ItemTemplate>
<tr>
<td class="col-item-actions">
<a id="aShare" runat="server" href="#modal-share" class="button button-small modal-trigger">Share</a>
</td>
</tr>
</ItemTemplate>
</asp:ListView>
I need to find the anchor tag and change its href dynamically using jquery.
Can any body please help me to solve this.
Thanks.
Since you have classes assigned. You could try:
$("#<%= lstview.ClientID %> .button").attr("href","yourhref");
or
$("#<%= lstview.ClientID %> .button-small").attr("href","yourhref");
Notice the lstview.ClientID because this is dynamically generated id.
$("#'<%=ListView.ClientID %>'").find("a").attr("href","srt your href");
reference attr

Getting ID from asp.net runat server in jQuery

I'm trying make some stuff in jQuery using ASP.NET. But the ID from runat="server" is not the same as the id used in HTML.
I used to use this to get the ID from this situation:
$("#<%=txtTest.ClientID%>").val();
But in this case, it does not work. I'm clueless as to why.
Javascript
/* Modal */
function contatoModal() {
//alert("Test");
alert($("#<%=txtTest.ClientID%>").val());
}
HTML
< input runat="server" id="txtTest" value="test" />
Any tips?
<%= txtTest.ClientID %> should work but not in a separate javascript file where server side scripts do not execute. Another possibility is to use a class selector:
<input runat="server" id="txtTest" value="test" class="txtTest" />
and then:
var value = $('.txtTest').val();
In WebForm / HTML Page....
<asp:TextBox ID="txtUserName" runat="server" Class="form-control"></asp:TextBox>
In Jquery
var UserName = $("[id*=txtUserName]").val();
alert(UserName);
100% Sure its Working for me....
As others have mentioned, you can pass a class selector to jQuery, but that is a bit messy. I prefer to use the jQuery attribute ends with selector. Given that a generated ID is a flattened hierarchy of controls, you can use the "ends with" selector to find your element.
<input runat="server" id="txtText" />
When rendered, the generated ID becomes something like this (if within a masterpage's content place holder):
<input id="ctl00_contentplaceholder_txtText" />
To find this control:
$("input[id$='txtText']")
Take caution when using this within a repeater.
Try putting it into a variable name:
var txtTestID = '#' + '<%=txtTest.ClientID %>';
$(txtTestID).val();
I'm not sure if the <%= likes being inside double quotes. I've always had mixed behaviors when not using the single quote.
When using ASP.NET 4 and the ClientIDMode is set to “Predictable”, you can predict the ID based on hierarchy. Or set it set to “Static”, so asp.net wont mess it up.
ScottGu's article on it http://weblogs.asp.net/scottgu/archive/2010/03/30/cleaner-html-markup-with-asp-net-4-web-forms-client-ids-vs-2010-and-net-4-0-series.aspx
And this is extremely useful when using external JS file scenarios.
As Darin Dimitrov said in his answer:
<%= txtTest.ClientID %> should work but not in a separate javascript
file where server side scripts do not execute.
The solutions that I could find for those are:
<input runat="server" id="txtTest" value="test" class="txtTest" />
Use class instead of ID
Using class you can retrieve the value anywhere. This is one of the best solutions (usually the best)
var value = $('.txtTest').val();
Use ClientID code in the aspx
You can always call ClientID in the aspx, but if you are working with some kind of structure, this isn't the best solution. I like to use this method when I'm testing something.
var value = $('#<%=txtTest.ClientID%>').val();
You can also use ClientID in a external js file with a workaround. IT'S NOT PRETTY, use only if you really need it. I usually do this when I use Telerik.
In the aspx:
var id = <%=txtTest.ClientID%>;
In the js file:
var value = $('#'+id).val();
Use Control.ClientIDMode Property Static
so the HTML becomes
<input runat="server" id="txtTest" value="test" ClientIDMode="Static" />
and the js can call it as it is named of
var value = $('#txtTest').val();
The problem with this solution is that you need to be very careful to avoid duplicity on the ids of your page. Try never use Static mode in a controller.
As states MSDN:
The ClientID value is set to the value of the ID property. If the
control is a naming container, the control is used as the top of the
hierarchy of naming containers for any controls that it contains.
The link of shaans's answer is a awesome place to check extra information about ClientIDMode.
Cleaner HTML Markup with ASP.NET 4 Web Forms - Client IDs (VS 2010 and .NET 4.0 Series)
To avoid issues with rendered ID's, use a class instead. This won't change during rendering:
function contatoModal() {
//alert("Test");
alert($(".txtTest").val());
}
HTML:
< input runat="server" id="txtTest" value="test" class="txtText" />
Adding a css class to the input and then using this class in jQuery to getting the input element will solve the issue.

Difference between ID and control.ClientID OR why use control.ClientID if I can access control through ID

This is the code from .aspx file
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>Login Again</title>
<script type="text/javascript">
function Validate() {
if (document.getElementById("txtLogin").value == "") {
alert("Enter login name.");
}
if (document.getElementById("<%=txtLogin.ClientID%>").value == "") {
alert("Enter login name.");
}
}
</script>
</head>
<body>
<form id="form1" runat="server">
<asp:TextBox ID="txtLogin" runat="server"></asp:TextBox>
<asp:Button ID="btnSubmit" runat="server" Text="Login" OnClientClick="Validate()" />
</form>
</body>
</html>
In function Validate() I can
access textbox using Id of control
i.e.; getElementById("txtLogin") so
should I use the second approach
which is accessing control through
control.ClientID and why?
My first understanding was that to
access server control I have to use
this syntax <%= %> but now I come
to know from this example that I can
access server side control simply
through
getElementById("ID-of-control").
The ID generated in the final HTML is not guaranteed to remain the same as the one in your aspx source. When you'll put the controls inside naming containers the ID will have prepended one or several parent ids to ensure its uniqueness. The ClientId property will always give you the final form of the ID attribute as it ends up in the HTML so it's always recommended to use that in your javascript.
Read this....
Quote from post...
All ASP.NET server controls include an
ID property that uniquely identifies
the control and is the means by which
the control is programmatically
accessed in the code-behind class.
Similarly, the elements in an HTML
document may include an id attribute
that uniquely identifies the element;
these id values are often used in
client-side script to programmatically
reference a particular HTML element.
Given this, you may assume that when
an ASP.NET server control is rendered
into HTML, its ID value is used as the
id value of the rendered HTML element.
This is not necessarily the case
because in certain circumstances a
single control with a single ID value
may appear multiple times in the
rendered markup....
Short answer is ClientID to ensure you find your control.
Which version of ASP.NET are you using? In .NET 4 you can specify not to autogenerate the IDs.
I think this is a coincidence in this case because youn are not using any user controls or other containers. Once you do you will no longer be able to guarentee that the controls ID will remain the same and thus you should use the second approach as a best practice because if your page is modified in the ways I have stated your javascript will no longer work and it may be difficult to see why at a later date.

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