Avoiding & when adding a JavaScript event handler using Attributes.Add()

[Nathan Sokalski]

I add a JavaScript event handler to some of my Webcontrols using the
Attributes.Add() method as follows:


Dim jscode as String = "return (event.keyCode>=65&&event.keyCode<=90);"
TextBox2.Attributes.Add("onKeyPress", jscode)


You will notice that jscode contains the JavaScript Logical And operator
(&&). However, ASP.NET renders this as &amp;&amp; in the code that is
output, even though it is intended to be client-side JavaScript, not a
visible onscreen character. How can I get ASP.NET to output


onKeyPress="return (event.keyCode>=65&&event.keyCode<=90);"

instead of

onKeyPress="return (event.keyCode>=65&amp;&amp;event.keyCode<=90);"


I am using VB.NET to write my server-side code, and am using Visual Studio
..NET 2003 with .NET 1.1. Thanks in advance for any help you can give.

 

[Guest]

Abstractly speaking .innerHTML or .innerText might solve the problem (?)

I just don’t know specifically where you can and/or want to try .innerText
or .innerHTML.

More of a general answer sorry I wish I had more time to look at it.

 

[Nathan Sokalski]

I don't think that either of those are part of the solution, because they
refer to the stuff between the opening and closing tags, like the following:

<HTMLTAG>innertext or innerhtml</HTMLTAG>

My goal is to add an attribute to the tag, which would be like the
following:

<HTMLTAG ATTRIBUTE="ATTRIBUTEVALUE"></HTMLTAG>

Using the Attributes.Add() method that I showed in my initial posting adds
the attribute to the right place, but it replaces the ATTRIBUTEVALUE's &'s
with &amp;'s, therefore causing the JavaScript to have incorrect syntax.

 

[Guest]

Ah..I see, yeah I have no idea either. Its clear that you have a clear
understanding what I was getting at and also how it doesnt apply to your
situation.

sorry about that.

 

[Nathan Sokalski]

Well, I haven't found a way to do it using ONLY the Attributes.Add() method
yet (if there is one, it might be unavoidable depending on how they coded
the Add() method), but I think I figured out a workaround that I think will
work for all situations. Rather than doing:


Dim jscode as String = "return (event.keyCode>=65&&event.keyCode<=90);"
TextBox2.Attributes.Add("onKeyPress", jscode)

I will do the following:

Dim jscode as String = "return (event.keyCode>=65&&event.keyCode<=90);"
Page.RegisterClientScriptBlock("TextBox2_RestrictInput", "<script
type=""text/javascript"">function TextBox2_RestrictInput(){" & jscode &
"}</script>")
TextBox2.Attributes.Add("onKeyPress", "return TextBox2_RestrictInput();")


This basically writes my JavaScript code as a function, and then I just
return the value returned by the function. Apparently
RegisterClientScriptBlock leaves the &'s alone, so it works. Maybe this is
how ASP.NET intended all generated JavaScript to be added, although I think
it would be nice to be able to do it without the RegisterClientScriptBlock
method, but I guess I'll have to deal with it this way for now.

 

[Scott M.]

Server.HTMLDecode("&amp;&amp;")

 

[Chris R. Timmons]

I add a JavaScript event handler to some of my Webcontrols using
the Attributes.Add() method as follows:


Dim jscode as String = "return
(event.keyCode>=65&&event.keyCode<=90);"
TextBox2.Attributes.Add("onKeyPress", jscode)


You will notice that jscode contains the JavaScript Logical And
operator (&&). However, ASP.NET renders this as &amp;&amp; in
the code that is output, even though it is intended to be
client-side JavaScript, not a visible onscreen character. How
can I get ASP.NET to output


onKeyPress="return (event.keyCode>=65&&event.keyCode<=90);"

instead of

onKeyPress="return
(event.keyCode>=65&amp;&amp;event.keyCode<=90);"


I am using VB.NET to write my server-side code, and am using
Visual Studio .NET 2003 with .NET 1.1. Thanks in advance for any
help you can give.

Nathan,

I think your solution of using Page.RegisterClientScriptBlock is
about the only reasonable thing that will work.

I used Reflector to trace thru
System.Web.UI.WebControlsWebControl.Attributes to see if it was doing
any kind of encoding. It turns out that
System.Web.HttpUtility.HtmlAttributeEncode is called on any text
added via Attributes.Add. As you've found out, HtmlAttributeEncode
turns & into &amp;. It also turns double quotes (") into &quot;.

 

[Nathan Sokalski]

That would return the String && which is what I am currently putting in. The
conversion to &amp;&amp; occurs somewhere between the call to
Attributes.Add() and the time that the page is sent to the browser. The
problem is that I don't know where, and if I did, I am not sure it is an
area of code that I have the ability to edit, because I think it is in some
area of the code that is part of ASP.NET, and I therefore do not have access
to the source code. I do still want to find a way to output characters
without having them go through what I think is the Server.HtmlEncode()
method, but I have found a reasonably simple workaround for doing what I was
trying to do that caused me to start this thread (see the message I posted
at 2/28/2006 7:32 PM for the workaround I found)

 

[Raymond]

Yup, I don't think there is any easy solution save the
workaround you used. Frankly, I think they got this
one wrong in ASP.NET. It does the html encoding
automatically on that method call. The only other
workaround I can think of is to use methods of the HtmlTextWriter
and simply write the whole element without the
encoding turned on. That's not as easy to pull off as your workaround
and may need a custom control.

The correct way for ASP.NET to have done this would've been to at least
turn off html encoding when "javascript:" is prepended to the text, or
better
yet, another parameter in that method for the encoding, just like one of the
overloads of the AddAttribute method of the HtmlTextWriter.