Hi,
No, you can't read it from a js file, since the links are created through the program, i.e. you put in the aI string coded for text, url= etc. The js program reads the url and converts it to a 'link'.
But, there is a way to do it without having to do it manually. There is an add-on that was created for the menu to allow use of a sitemap. This add on creates a ul list that opens in a new window. You can use this list to test your links
Here is the demo for that site index.
http://support.milonic.com/demos/site_index/index.htm
I use this. If you don't want to put the site index option in the menu on the web, then you need to save your data file twice, once as you want it, then add the site index option and save it under a different name. Put that one on a page so you can create the site index, then use the site index page that opens to test all the links. It's a lot easier than it sounds, and much longer to explain than to do it

You just have to remember when you update your menu and want to check links again, to also update the other file [if you make a separate one]
Hope that made sense!
Ruth