Just to refresh our memories, "myscript.js" should contain the script itself minus the surrounding <script></script> tags, and saved as a text file (but with .js extension).
Now, the nature of JS libraries means that they're not only accessible by your site/domain, but anyone's. Like an image, a library could potentially be utilized by any site that decides they like your script but not the bandwidth associated with it. Specifically, they would simply use a syntax like the following on their page:
This can become a headache, especially if the library is very large.