How to convert string to HTML safe string

Question

I am creating a some dynamically generated HTML

bldr.AppendLine("<a>");
string userText = user.Company;
bldr.AppendLine(userText);
bldr.AppendLine("</a>");

How can I ensure that whatever the company's name is, will appear as it should, but also if they try to inject any HTML in thier name it will simply appear in plain text.

For instance if they tried to use the name "<script>alert("Do Bad!")</script>" that's exactly what will appear on the page, in plain text.

But I also want to avoid "A & C" translating to "A \u0026 C", which is what happens when I use

HttpUtility.JavaScriptStringEncode(user.Company);

Answer 1

using System.Web;

var encoded = HttpUtility.HtmlEncode(unencoded);

Answer 2

An alternative without a dependency to System.Web:

System.Net.WebUtility.HtmlEncode()

Answer 3

You can use the HttpUtility.HtmlEncode method:

var htmlString = HttpUtility.HtmlEncode(user.Company);

Answer 4

HtmlUtility.HtmlEncode(string s)

Answer 5

You can use the same class HttpUtility you have use to javascript, but, for html, for sample:

bldr.AppendFormat("<a>{0}</a>\n", HttpUtility.HtmlEncode(user.Company));

There is also the inverse way using HttpUtility.HtmlDecode(string).