Unescape HTML entities in Javascript?

I have some Javascript code that communicates with an XML-RPC backend. The XML-RPC returns strings of the form:

<img src='myimage.jpg'>

However, when I use the Javascript to insert the strings into HTML, they render literally. I don't see an image, I literally see the string:

<img src='myimage.jpg'>

My guess is that the HTML is being escaped over the XML-RPC channel.

How can I unescape the string in Javascript? I tried the techniques on this page, unsuccessfully: http://paulschreiber.com/blog/2008/09/20/javascript-how-to-unescape-html-entities/

What are other ways to diagnose the issue?