swf2js is Flash Player Runtime Engine written in pure JavaScript
This script should not be not be installed directly. It is a library for other scripts to include with the meta directive // @require https://update.greasyfork.org/scripts/466069/1189642/swf2js.js
This is a JavaScript FlashPlayer emulator that analyzes SWF files (Flash) in real time and converts them to HTML. It supports SWFs for Flex, Flash, Animate, and all platforms.
For more info: Homepage, Source code and Library