This SO answer says NO:
$(document).ready is for assurance full DOM is available at the time the function is called. Any functions and events not depending on the DOM don't need to be put into the ready event.
This technique works somewhat like this:
This new element loads the source file file1.js. The file begins downloading as soon as the element is added to the page. The important thing about this technique is that the file is downloaded and executed without blocking other page processes, regardless of where the download is initiated. You can even place this code in the header of a document without affecting the rest of the page (aside from the one HTTP connection that is used to download the file).