JavaScript is a popular scripting language with a syntax very similar to Java and Groovy. JavaScript has a set of functions and object methods that in some cases differ from Java and Groovy. For example, the method String.startsWith(...) does not exist in JavaScript. You can still use Java objects in JavaScript. An example is:

(new java.lang.String("test")).startsWith("t")

This is a valid JavaScript expression creating a Java object (in this case a java.lang.String) and using its methods.

JavaScript is the best choice for users who have no knowledge of other languages. The other significant advantage of JavaScript is that it is not interpreted at run time, but instead generates pure Java byte-code. As a result, it offers almost the same performance as Java itself.