radiobuttonlist and javascript RSS

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  Frum

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  radiobuttonlist and javascript

  Jul 21, 2003 12:28 PM|LINK

  hi I have a checkbox and a radiobuttonlist (the radiobuttonlist contains 2 items) in my form. The radiobuttonlist has its visible property set to false at design time. At run time, when the checkbox is checked, then I want the radiobuttonlist to appear. I want to use javascript. On Form_Load I've done:

  chkM.Attributes.Add("onclick", "ShowPeriod('" & RDLPeriod.ClientId & "');return false;")

  The HTML Source:

  
       
  	Monthly 
  	
       
       
          Period 
          
   	  All
  	  Current Year
          
      
   

  In the script section I have:

  function ShowPeriod(w) 
  {
     document.all(w).visible=true;
     //document.getElementById("RDLPeriod").style.visibility=true;
  }	

  Upon execution, when I check the checkbox, the code breaks in the script section and tells that : 'document.all(...)' is null or not an object Where is the problem guys ?
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  CarlosAg

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  Re: radiobuttonlist and javascript

  Jul 22, 2003 07:58 AM|LINK

  If you set visible=false in the server, then the control usually does not render its markup, only ViewState, so then it will not be in the Html. Try doing a "View Source" in your browser and see if it is there. So if it is not, then you will need to set Visible=true in the server and in the window_onload in client side script, you can make it invisible (style='display:none' or try adding this style with the attribute collection) and then make it visible as your code does.
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  autofed

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  Re: radiobuttonlist and javascript

  Jul 22, 2003 08:01 AM|LINK

  One of the great advantages of ASP.NET is being able to use postbacks to perform actions instead of relying on javascript. Try handling the chkM.Click event and making the radiobuttonlist visible there. AutoFed
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  Frum

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  Re: radiobuttonlist and javascript

  Jul 22, 2003 09:31 AM|LINK

  Autofed: The postback is indeed a great advantage but imagine about hundreds of postbacks in the same form... In some cases, I prefer javascript though as it does not do this postback (refresh) of the screen. As CarlosAg rightly pointed out that a server side control having its visible property set to false is not rendered in the HTML. I just learnt that too. So using the attributes collection I'm trying to hide it but it's not working, can u see any problem: Dim bodyControl As New HtmlGenericControl("body") bodyControl.Attributes.Add("onload", "javascript:alert('hello');")
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  autofed

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  Re: radiobuttonlist and javascript

  Jul 22, 2003 09:19 PM|LINK

  You are creating a new body control. This won't help you, since there is already a body "control" explicitly declared. Add an id attribute to the body tag in your aspx page. Then use Page.FindControl(id) to access the body tag, and add the onload attribute to it. AutoFed
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  Frum

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  Re: radiobuttonlist and javascript

  Aug 01, 2003 10:06 AM|LINK

  hi there (sorry for the late reply but got stuck in another problem) I gave an id to the body tag and called it bodyID me.FindControl("bodyID").Attributes.Add .... does not work since me.FindControl("bodyID") does not support the Attributes.Add method.... Can u help?
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  adec

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  Re: radiobuttonlist and javascript

  Aug 01, 2003 11:08 AM|LINK

  Do like this:

  Dim body As HtmlControl = Ctype(FindControl("bodyID", HtmlControl)
  body.Attributes.Add("[Key]", "[Value]")

  Regards
  Andre Colbiornsen
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  Frum

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  Re: radiobuttonlist and javascript

  Aug 01, 2003 11:43 AM|LINK

  thanks adec for your reply the code looks ok. I tried something similar in codebehind on page_load:

  Dim body As HtmlControl = CType(FindControl("bodyID"), HtmlControl)
   body.Attributes.Add("onload", "javascript:alert('hello');")

  I'm getting: Object reference not set to an instance of an object Do u think because at that point the body is still being loaded or ... ? what do u propose ?
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  CarlosAg

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  Re: radiobuttonlist and javascript

  Aug 01, 2003 07:12 PM|LINK

  Did you put the runat server attribute to the Body tag (and also the id bodyID) ?
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  Frum

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  Re: radiobuttonlist and javascript

  Aug 04, 2003 07:41 AM|LINK

  thanks Carlos I had not included the runat="server". Now it works!