gistfile1.el

(defvar mo-script-url-alist
  '((jquery . "https://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js")
    (json2 . "http://cdnjs.cloudflare.com/ajax/libs/json2/20110223/json2.js")
    (ocanvas . "http://cdnjs.cloudflare.com/ajax/libs/ocanvas/1.0/ocanvas.min.js")
    (processing . "http://cdnjs.cloudflare.com/ajax/libs/processing.js/1.2.1/processing-api.min.js")
    (prototype . "https://ajax.googleapis.com/ajax/libs/prototype/1.7.0.0/prototype.js")
    (sizzle . "http://cdnjs.cloudflare.com/ajax/libs/sizzle/1.4.4/sizzle.min.js")
    (underscore . "http://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.1.7/underscore-min.js")
    (underscore-string . "http://cdnjs.cloudflare.com/ajax/libs/underscore.string/1.1.4/underscore.string.min.js")
    (waypoints . "http://cdnjs.cloudflare.com/ajax/libs/waypoints/1.1/waypoints.min.js"))
  "URLs for loading different JavaScript libraries.")

(defun mo-get-script-url (library)
  "Get a script URL for the given library."
  (cdr (assoc library mo-script-url-alist)))

(defun mo-script-tag-insert-for-library (library)
  (let ((script-url (mo-get-script-url library)))
    (concat "var script = document.createElement('script'); "
	    "script.type = 'text/javascript'; "
	    "script.src='" script-url "'; "
	    "head.appendChild(script);" )))