It is Microsoft JScript (similar to JavaScript) which is ECMAScript 3 (ES3 (Dec 1999)) compatible. As such, some functionality that you might find on the internet does not apply, such as new functionality added in ES5 (Dec 2009), ES6 (2015), or ES7 (2016).
See here for good reference on the Helper and API extensions that were added to the Scripting Engine in SambaPOS …