Webstorage
Example of level editor (basic, WIP, with saving system) - LINK
Save variables/example of use of webstorage - LINK
Other example of use of webstorage - LINK
This is not exactly one action "Save my whole array" type of thing, but you have to consider HTML5 limitations (like no support of the mousewheel or no system file access (no writing to the harddrive, apart from webstorage)).