What is the shortest snippet that emulates `include` in JavaScript without third-party scripts?
Here is what I do:

var a_script= document.createElement('script');
a_script.src = 'http://www.blah.com/some_script.js';
document.head.appendChild(a_script);


I should mention that in production I pretty much always combine all javascript files into one larger, minified, and google closure compiled file.