using System;

using System.Text;

using System.Web;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        // encode tout

        Console.WriteLine(HttpUtility.JavaScriptStringEncode(@"Héllo World%#@$^^&""\"));

        // encode explicitement certain contenu

        Console.WriteLine(EncodeJavaScriptString(@"Héllo World%#@$^^&""\"));

    }

​

    public static string EncodeJavaScriptString(string s)

        => string.Concat(s.Select(c => {

            switch (c)

            {

                case '\"': return "\\\"";

                case '\\': return "\\\\";

                case '\b': return "\\b";

                case '\f': return "\\f";

                case '\n': return "\\n";

                case '\r': return "\\r";

                case '\t': return "\\t";

                default: return (c < 32 || c > 127) && !char.IsLetterOrDigit(c) ? $"\\u{(int)c:X04}" : c.ToString();

            }}));

}