JerryScript is a lightweight JavaScript engine optimized for microcontrollers and embedded devices. It has a small memory footprint of only 3KB and implements ECMAScript 5.1. JerryScript has been ported to run on the Internet of Things (IoT) operating system RIOT, allowing JavaScript code to easily be run on microcontrollers. A demo of JerryScript running a Tetris game on an STM32F4 board using an LED matrix was shown. Future work includes further optimizations and adding debugging support to JerryScript.