Replacing tag content with html string

I have the following xml:

<foo><toReplace/></foo>

I want to replace <toReplace/> tag with the following string:

"<b>bar</b>"

How can I do that?

Right now I have the following code:

var xml = "<foo><toReplace/></foo>";
var parser = new dom.DOMParser().parseFromString(xml, "text/xml");
parser.getElementsByTagName("toReplacce")[0].textNode = "<b>bar</b>";
console.log(parser.toString()); // "<foo>&lt;b>bar&lt;/b>"

The problem is that is escapes HTML. How can I replace the content with the HTML string here?

via user99999