How to decode a string encoded with JavaScriptStringEncoded?

Question

Is there a method to decode a string encoded with HttpUtility.JavaScriptStringEncode() in C#?

Example encoded string:

<div class=\"header\"><h2>\u00FC<\/h2><script>\n<\/script>\n

My temporary solution is:

public static string JavaScriptStringDecode(string source)
{
    // Replace some chars.
    var decoded = source.Replace(@"\'", "'")
                .Replace(@"\""", @"""")
                .Replace(@"\/", "/")
                .Replace(@"\t", "\t")
                .Replace(@"\n", "\n");

    // Replace unicode escaped text.
    var rx = new Regex(@"\\[uU]([0-9A-F]{4})");

    decoded = rx.Replace(decoded, match => ((char)Int32.Parse(match.Value.Substring(2), NumberStyles.HexNumber))
                                            .ToString(CultureInfo.InvariantCulture));

    return decoded;
}

Answer 1

System.Text.Json.JsonSerializer.Deserialize(string json) will do it for you except the case when original string was null - it returns "" instead.Do not forget to put encoded string inside double quotes before. HttpUtility.JavaScriptStringEncode(str,true) overload will do it automatically.