ai-resize-layers-to-artboard
Adobe Illustrator jsx script to loop through and resize each layer's artwork to fit proportionally inside the artboard.
Works in CC2014 (should work in later versions).
Doesn't work in CS3 (and probably won't work in earlier versions).
Based on the fine work of these folks:
Carlos Canto, dbburgess and ruandre
https://forums.adobe.com/message/4164590
http://aiscripts.com/2012/09/fit-object-to-artboard/
https://gist.github.com/ruandre/7b47cbf2a4c55dac9adb
How to use:
Run the script from the File > Scripts > Other Script menu. Or copy it into the following folder to make it available directly from the Scripts menu: Adobe Illustrator CC 2014 > Presets > en_US > Scripts