Аннотация:This paper aims to present JerryScript, a JavaScript engine for the Internet of Things (IoT). This lightweight JavaScript engine intended to run on very constrained devices such as microcontrollers, which have only a few kilobytes of RAM available to the engine (<64 KB RAM) and constrained ROM space for the code of the engine (<200 KB ROM). The engine is ECMA-262 5.1 compliant, supports on-device compilation, execution, and provides access to peripherals from JavaScript. It powers the IoT.js project, which provides an interoperable service platform in the world of web-based IoT. This demonstration proves that usage of JavaScript on every constrained device is reasonable and profitable.