HtmlSpecialChars equivalent in Javascript?

Answer 1

That's HTML Encoding. There's no native javascript function to do that, but you can google and get some nicely done up ones.

E.g. http://sanzon.wordpress.com/2008/05/01/neat-little-html-encoding-trick-in-javascript/

EDIT:
This is what I've tested:

var div = document.createElement('div');
  var text = document.createTextNode('<htmltag/>');
  div.appendChild(text);
  console.log(div.innerHTML);

Output: <htmltag/>

Answer 2

With jQuery it can be like this:

var escapedValue = $('<div/>').text(value).html();

From related question http://stackoverflow.com/questions/24816/escaping-html-strings-with-jquery