From topic: http://stackoverflow.com/questions/9791403/how-to-get-actual-not-original-height-of-a-css-rotated-element
its about getting height of a rotated element.
FileReader allows you to load json files and it parses it into global var of json. Made for so topic: http://stackoverflow.com/questions/22268481/read-local-json-file-in-firefox-extension