Javascript string in C# escaping issue

Question

I am having a problem with javascript.

The javascript gets created dynamically on a C# winforms project as a string.

The actual javascript code gets generated fine and all the double quotes get escaped as they should. My problem comes in when I assign a string inside of this function such as

string js = "eval(\"var someVar = 'someValue'\");";

So I end up with a string in the browser as

eval(\"var someVar = 'someValue'\");

The problem is the "\" that is escaping the " in front of 'someVar'. It gets put in automatically in C#. That makes the string invalid when trying to execute the actual function in a browser. Any ideas how I might go about solving this?

Thanks.

Can you change the C-notso-# code that produces this atrocious JavaScript? There isn't really a good reason to use eval. Does C# have a JSON-encoder, or is there a library that does this for you? — Halcyon
– Halcyon, Commented Aug 12, 2013 at 12:01
I am not really using eval. The example suffices in showing the final product. And yes, I can change the code. Do you have any suggestions? — William
– William, Commented Aug 12, 2013 at 12:02
The javascript gets saved inside of <script> tags inside of an iFrame. The iFrame string gets sent to the front view and the entire frame appended to a predetermined child. — William
– William, Commented Aug 12, 2013 at 12:06

Miller · Accepted Answer · 2013-08-12 12:23:22Z

1

You can check HttpUtility.JavaScriptStringEncode Method if you are using .net 4 or later framework

edited Aug 12, 2013 at 12:23

answered Aug 12, 2013 at 12:18

Miller

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Comments

frenchie · Accepted Answer · 2013-08-12 12:27:58Z

1

You shouldn't need eval. This is how I do what you're trying to do.

Step 1: set up a Literal object on your aspx page. I put the literal in a hidden div.

<div style="display:none;" id="TheDiv">
   <asp:Literal runat="server" ID="TheLiteral" />
</div>

Step 2: inject the value in the literal into the C# code behind file.

TheLiteral.Text = SomeValue;
TheLiteral.Text = SomeValue.ToString(); // in case SomeValue is not a string

Step 3: get the value from the client:

var SomeVar = $('#TheDiv').text();
$('#TheDiv').remove();

For sure, there are other ways of doing it as well but this method works for me.

answered Aug 12, 2013 at 12:27

frenchie

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4 Comments

William Over a year ago

I am not using asp.net, but rather winforms.

frenchie Over a year ago

I don't understand: where's the javascript running? Are you building a web application or a desktop application?

William Over a year ago

It's not running anywhere. Rather the javascript get created in a desktop application, but then will at a later stage run on a web application.

frenchie Over a year ago

This sounds like a really weird plan. Anyway, another alternative would be to create a JSON string that you can parse in javascript: "{SomeVar:" + SomeValue + "}";

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