I have a page that's derived from a master page. On this page, I have a hiddenfield ("hfUser"). How can I access this "hfUser" control and get/set its value using JQuery?
I've tried variants of this:
$(document).ready(function() {
var test = $("#hfUser").val();
alert(test);
});
but test = undefined. I'm guessing I've got the selector wrong, but I don't know how to get an asp hiddenfield. Any ideas?
Thanks
If you are using Asp.net controls, the server will mangle the control ids. It adds a bunch of extraneous control tree hierarchy information into the id. You need to reference what that acutal id is that's getting rendered, which is availble with the ClientID property on the control (hfUser.ClientID) or access your control in a different, more roundabout way, like find the controls parent, then search through its children to find your control.
If you don't have to use the asp.net HiddenField control, try just using a regular old html input.
ASP does like to mangle ID's. The further down the rabbit hole (or nesting controls) you go, the more ASP adds to your control ID. Throw in Master Pages, and it's yet another level or two.
Another way to access server-side controls (with the runat property set), is to use the square brackets in your jQuery selector.
Like this:
$("[id$='hidImgSource']").val()
That selects any elements whose ID has 'hidImgSource' as ending part of the name. So it will find mangled ID's.
Here is a link to the jQuery Selectors page that explains some more options.
If the hidden field is an ASP.NET control, check out this blog post to help you with jQuery selectors for ASP.NET controls
http://www.foliotek.com/devblog/extending-jquery-to-select-asp-controls/
Do it like this:
$(document).ready(function()
{
var test = $("**#<%= hfUser.ClientID %>**").val();
alert(test);
});
Related
I am facing issues when I tried to add same custom control twice in the same page. The issue is because instance of one control is caling the java script of the other. Added to that I am using ajax popup extender where in I have popup divs with in that control itself.
Now it is leading to java script errors because it is geting confused among the popup div ids and scripts etc.
Please help me.
Take one step further in taking care about client-side IDs generated uniquely for the tags inside each instance of your custom control.
This can be easily fixed by adding runat="server" attributes to the tags which you want to have unique client side IDs when rendered to the browser. Then you should use this kind of code in JS:
document.getElementById("<%= control.ClientID %>");
As about tags which you don't want to mark using runat attribute, you can assign them their IDs uniquely on the server-side manually in each instance of the custom control.
I hope this helps!
There's no automatic fix for this. If a custom control is going to be used more than once on a page, you have to design it to be aware of this. In particular, you'll probably need to refer to generated elements using their generated id:
var ele = document.getElementById("<%= serverSideControl.ClientID %>");
Javascript emitted by the control will have to also emit the appropriate ID's.
And so on.
I have an asp.net page with several list boxes.
I would like to include some javascript on the page that allows a user to drag individual list elements from one box to another.
On a normal web page, the script to do this is reasonably simple, however, with the element IDs generated by ASP.NET, I don't know what identifiers to have my script look up?
Any thoughts on how to do something like this?
Add a identifying CSS class to your elements and use those. i.e. jQuery has a superb support for that so you can grab all elements and loop through them to do whatever you want.
Check out the ClientId property of the Control class.
Note: The ASP.NET ListBox control inherits from Control.
Update
In reponse to the comments below, I can think of two ways to access the individual li elements of an unordered / ordered list generated by the ListBox control.
Create a custom Control that inherits from
the ListBox control and renders out an
id attribute for each li element.
Use the getElementsByTagName method
in JavaScript. MSDN even has an
example that uses the
getElementsByTagName method to get
the children of an unordered list and
displays an alert indicating the
number of children and the value of
the first child element. If the MSDN documentation isn't your thing, you can check out the MDC documentation as well.
You could either use the ClientId property as stated by paper1337
var element = document.getElementById('<%= MyDropDownList.ClientID %>');
or you could implement a AJAX Behavior using AjaxControlToolkit.
Code:
[assembly: WebResource("MyJS.js", "text/javascript")]
[ClientScriptResource("MyBehavior", "MyJS.js")]
public sealed class MyExtender : BehaviorBase {
// can be empty
}
Markup:
<asp:DropDownList runat="server" ID="DDL" />
<my:MyExtender runat="server" TargetControl="DDL" />
MyJS.js (See AjaxControlToolkit samples for details):
...
var element = this.get_element();
...
If you are on asp.net 4.0+, you can use the ClientIDMode="Static" to force asp.net to use the id you have specified. There's a nice explanation on ScottGu's blog, and the MSDN Docs for ClientIDMode are available.
You may also want to try ClientIdMode="Predictable", if you have a lot of generated elements.
More
I have this datalist in a user control i want when i keep mouse over "More", it should be invisible. it is working on .aspx page not on user control. How to do this. This control is placed on master page.
Please Help.
Probably it will be an issue with getElementById. In a naming container you cannot get the element by simply giving its id. You have to use ClientID to get the generated id of the element at runtime.
Something like
document.getElementById ( "<%= DataList2.ClientID %>");
See Control.ClientID Property
and
Control ID Naming in Content Pages
I would agree that it's probably an issue with trying to get the id of the element since the element's id changes at runtime when you put it inside a user control. You can run your code then do a view source in the browser and see exactly what the id is generating to at runtime.
Have you tried debugging the javascript mover() and mout() function? I am guessing you are looking for elements with the wrong id's since the id's are probably different inside a user control.
document.getelementbyid('txtbox') is not working when I used in content page as it is working in the normal web page. The value is null when it is used in contentpage. Plz anybody help me
The id will have changed, you can use something like:
document.getelementbyid(<%=txtTextBox.ClientID%>).value
or you can view the source to get the id in the hopes that it will not change again.
If you have the option I'd switch to some other engine, such as asp.net mvc where you have control over the HTML.
When the page renders, if the textBox is under another control, the Id tends to change.
You can use the ClientId property:
document.getElementById("<%= txtbox.ClientID %>")
Read this article
Control ID Naming in Content Pages
ASP.NET allows certain controls to be
denoted as naming containers. A naming
container serves as a new ID
namespace. Any server controls that
appear within the naming container
have their rendered id value prefixed
with the ID of the naming container
control.
Naming containers not only change the
rendered id attribute value, but also
affect how the control may be
programmatically referenced from the
ASP.NET page's code-behind class. The
FindControl("controlID") method is
commonly used to programmatically
reference a Web control. However,
FindControl does not penetrate through
naming containers. Consequently, you
cannot directly use the
Page.FindControl method to reference
controls within a GridView or other
naming container.
Master pages and ContentPlaceHolders
are both implemented as naming
containers.
I have asp.net form that contains fields. When I access this window, my javascript functions can access the fields via the DOM with the getElementById() method and when I postpack to the server I am receiving the updates made by the client.
However, when I launch the form as a child window using Telerik's RadWindow control, the javascript can not access the hidden fields on the child form. Instead I get null.
My questions are:
Are hidden fields on a child window
not accessible when the window is
launched from a parent asp.net form?
Has anyone attempted this with Telerik controls and run into issues?
EDIT
Craig pointed out that the id may be different. Two additional questions then:
Can you ensure that the id you assign at the server is actually used?
Is using getElementByName() a better mechanism to access DOM elements?
To get the ID of your asp.net control do something like this:
<%= theControl.ClientID %>
getElementByName is not as commonly used as getElementById. The ID attribute is supposed to be unique for each element on the page whereas the name attribute can be duplicated.
It is quite possible that the element's ID is not what you think it is. Check the rendered page and see if the ID is there. I am guessing that the page is given a different ID since it is rendered inside another control.
If that is the case, you can have the form render some script that returns the element ID by accessing the controls client ID.
David, I'm sending you this answer because I saw the same issue in my code, and the only REAL solution I found was that I had to support the "OnClick" function in two places... In my case, I was using PetersDatePackage, but it was on a Telerik RAD Strip.
In my case, the control was on a .ascx page, and the JS code was as follows:
function OnIncidentDateChange(ctrl, dtDate, bErr)
{
var weekday = new Array(7);
weekday[0] = "Sunday";
weekday[1] = "Monday";
weekday[2] = "Tuesday";
weekday[3] = "Wednesday";
weekday[4] = "Thursday";
weekday[5] = "Friday";
weekday[6] = "Saturday";
<%=LabelDayOfWeek.ClientID %>.innerText = weekday[dtDate.getDay()];
}
But, this itself was not enough. I had to add THIS code to my parent page. The page that holds the controls for the Telerik strip.
// Dummy function?
function OnIncidentDateChange()
{
}
Once I did that, it worked...
I'm not certain why, to tell you the truth, and it makes no sense to me, and may just be a issue with the PDP package...
I use getElementsByName for checkboxes within the same group.
As for the control's ID, TonyB has the right idea, but make sure you refer to the ClientID property in the PreRender event handler, because if you do it too early in the page life cycle, it will not be available yet).
Is it possible the that javascript is trying to get a reference to the hidden field before the RadWindow has loaded it? I believe I've run into this before and had to use setTimeout to get around the problem.