Javascript: How to check boolean value from code-behind in ASP.NET

Question

I have a boolean property in code-behind ASP.NET, now I want to use it in Javascript of mark-up file, but Javascript do not understand True, or False. SO now, I'm using this:

if ( '<%=IsTabVisible%>' == 'True'){
///
}

It works, but quite ugly. Is there a better way to do this?

Thank you

What does the generated code look like?

Felix Kling
– Felix Kling

2011-07-28 06:46:24 +00:00
Commented Jul 28, 2011 at 6:46 — Felix Kling
– Felix Kling, Commented Jul 28, 2011 at 6:46

nnnnnn · Accepted Answer · 2011-07-28 07:16:19Z

15

The way I see it you have three options:

A. Do what you are already doing.

B. Perform the if test on the server-side, something like this:

<% if (IsTabVisible) { %>
    // client-side code here, whatever you had inside the brackets
    // of your original if statement
<% } %>

C. Make sure you generate 'true' and 'false' in lowercase so that it will work as client-side JavaScript, something like this:

if (<%= IsTabVisible ? "true" : "false" %>)

Which will appear to the client as:

if (true)

or

if (false)

Option A may look a bit funny but it works fine. Option C produces pretty client-side code that probably nobody will see. My preference is Option B.

answered Jul 28, 2011 at 7:16

nnnnnn

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2 Comments

ToastyMallows Over a year ago

Option C makes Visual Studio complain, a bunch of errors on the page like Syntax error and Expected ')', I think because the Javascript thinks you have an empty if() statement. Did this work at some point and is now broken or what?

nnnnnn Over a year ago

@ToastyMallows - Option C uses valid C# which produces valid JavaScript. I haven't used Visual Studio since 2011, but back then it sometimes used to report JS "errors" or warnings for valid JS because it got confused if server-side code was mixed into the JS - but the code would still run.

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