It's basically a Chrome web browser extension with some code that runs automatically in the background to add Web Bluetooth support - so you can use the Web IDE at https://www.espruino.com/ide without requiring the huge installer for the 'Native IDE'.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Last week, urish posted up a web bluetooth polyfill that he made: https://github.com/urish/web-bluetooth-polyfill#installation
It's basically a Chrome web browser extension with some code that runs automatically in the background to add Web Bluetooth support - so you can use the Web IDE at https://www.espruino.com/ide without requiring the huge installer for the 'Native IDE'.
It also means that other Web Bluetooth examples should work, like these: http://www.espruino.com/Puck.js+Web+Bluetooth
Please let us know how you get on!