ASP.NET control with visible=false cannot be used in javascript?

Question

I have an ASP.NET text control "FromDate" whose visible property is set to false, but I wanted a client side javascript to be able to toggle the visibility property using CSS properties

element1.style.display = "none"; // hides the element
element1.style.display = ""; // shows the element

but when I attempt to get the textbox, I get null on

  var element1 = document.getElementById("FromDate");

When I try the same code with visble=true as the default on the "FromDate" ASP.NET control, it works (although that is not the behavior I need)

Any ideas?

Gabriel McAdams · Accepted Answer · 2010-01-03 22:34:42Z

22

When you set Visible = false to a control, it is not rendered. That means there is no HTML representation of that control sent to the page. Set the style only.

You can set the style as display: none from server side code like this:

FromDate.Style.Add(HtmlTextWriterStyle.Display, "none")

answered Jan 3, 2010 at 22:34

Gabriel McAdams

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6 Comments

Ufuk Hacıoğulları Over a year ago

Can events be called when visible is false? Asked for security concern.

Gabriel McAdams Over a year ago

@Ufuk: What kind of events? JavaScript events cannot be called because there is nothing on the client. Server side events can still be called (Although the control may have been written such that the events wont be raised if its Visible property is set to false).

Ufuk Hacıoğulları Over a year ago

Server side events like button click. If somebody messes with postback, can they trigger those events?

Gabriel McAdams Over a year ago

I've never tried it. Maybe EventValidation would stop it. Give it a try.

Sarsaparilla Over a year ago

Important question: can a hacker change the control's value if visible=false?

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MikeD · Accepted Answer · 2013-05-14 12:46:09Z

14

If you want to hide this control, you can try CSS like this:

<asp:somecontrol id="FromDate" style="display:none" />

I think hiding the control with CSS is easier to understand.

edited May 14, 2013 at 12:46

MikeD

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answered Jan 4, 2010 at 3:00

Allen Le

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Comments

Aviad P. · Accepted Answer · 2010-01-03 22:35:09Z

3

Instead of setting Visible=false, set its style.display to none, that way the element is still there for JavaScript to manipulate.

answered Jan 3, 2010 at 22:35

Aviad P.

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