Escaping JavaScript string literals in views - asp.net-mvc

Question

Is there a utility function for escaping JavaScript in ASP.NET MVC views? I often need to init a little snippet of JavaScript using some values from the view; for instance I may have something like:
<script type="text/javascript">
var page = new Page({ currentUser: "<%= Model.UserName %>" });
page.init();
</script>
I would expect something like:
<script type="text/javascript">
var page = new Page({ currentUser: "<%= Html.JavaScriptEscape(Model.UserName) %>" });
page.init();
</script>
I could, of course, write the function myself. But since there are already built-in utilities form HTML encoding, and since one of the selling points of ASP.NET MVC is that the <% %> is the default rendering mode, and since what I'm trying to achieve is quite common, it makes me wonder why I cannot find anything like that already built-in. Is there, for instance, an easy and elegant way to serialize an object to JSON in views?
Or am doing something against ASP.NET MVC principles? When I hit a problem like this, it usually makes it think that either I’m doing something wrong since I assume that the framework designers spent some time thinking about real world scenarios.

Answer 1

In .NET 4, The HttpUtility class has a variety of static encoding methods for various contexts, including a JavaScriptStringEncode method for this particular purpose.
It's often simpler to just use JSON deserialization, though.

Answer 2

In MVC 5 using Razor templates, the following is possible:
<script type="text/javascript">
var page = new Page({ currentUser: #Html.Raw(Json.Encode(Model.UserName)) });
page.init();
</script>

Answer 3

After some time working in ASP.NET MVC, I concluded that (most likely) there is no build-in helper for it. Of course, it's trivial to write your own. Here is it for the sake of completeness:
using System.Web.Mvc;
using System.Web.Script.Serialization;
namespace MyProject.Helpers
{
public static class JsonExtensions
{
public static string Json(this HtmlHelper html, object obj)
{
JavaScriptSerializer jsonSerializer = new JavaScriptSerializer();
return jsonSerializer.Serialize(obj);
}
}
}
In a view, it can be used as follows:
<script type="text/javascript">
var page = new Page(<%= Html.Json(new { currentUser: Model.UserName } ) %>);
page.init();
</script>

Answer 4

In my case I needed a string not a json object and this is for Asp.Net Core:
#functions{
public Microsoft.AspNetCore.Html.IHtmlContent ToJS(string value)
{
return Html.Raw("'" + value.Replace("'", "\\'").Replace("\r", "\\r").Replace("\n", "\\n") + "'");
}
public Microsoft.AspNetCore.Html.IHtmlContent ToJS(int value)
{
return Html.Raw("" + value);
}
}
This will escape the ' and end of line characters. Also it leaves numbers (int) as a number. This could be overloaded to include float, decimal, etc. as needed.
So, I don't have to think about it or do anything different for each type:
var serverName = #ToJS(m.ServerName);
var appSiteUrl = #ToJS(m.SiteUrl);
var facebookId = #ToJS(m.FacebookAppId);