How to Activate ES6 Support in Nashorn under JDK 9

For the last few years, I have been using JavaScript on JDK for my programming tasks. At first (around 2009), I used to use Rhino, which is a JS engine developed by Mozilla. Rhino was included in JDK 6. Since JDK 8, Nashorn JavaScript engine was added to JDK as a replacement for Rhino. Its most important feature is its higher speed. In the newest version of Java, i.e. JDK 9, ES6 features have been added to Nashorn. However, these features are not activated by default. You can activate them by using the --language=es6 switch, like this:

java jdk.nashorn.tools.Shell --language=es6 file.js -- args

This adds newer JS features to Nashorn, including arrow functions, support for symbols, iterator protocol, Map and Set collections, templates, binary and octal numbers, and some other features as well.