just like the plugin builder is not conventional. I invite you to turn this code into a html file and open it in all of your browsers. you will find that even good old Microsoft Word displays the mark up correctly.
<p>The content of the body element is displayed in the browser window.</p>
<p>The content of the title element is displayed in the browser tab, in favorites and in search engine results.</p>
For your case above in the header section, place
inside the head section or depending on what your building maybe something like,
div = $('<div><body><script src="http://example.com/script.js"></script></body></div>');
apply logic to your plugin testing and most conventional methods will be soft guidelines.