The ELK is implemented small, but sufficient to create work scenarios, a subset of the ECMAScript Specification 6. In particular, a basic set of operators and types is supported, but there is no support for arrays, prototypes, this, new and delete expressions. Instead of VAR and Const, it is proposed to use LET, and instead of Do, Switch and For – While. The standard library is not provided, i.e. There are no such objects
Date, Regexp, Function, String and Number.