In a nutshell, the integration of JavaScript into Java opens up possibilities for creating standalone JavaScript programs and embedding JavaScript code within Java applications. While Java needs to be compiled into machine language before execution, JavaScript is text-based and interpreted directly by web browsers. This cross-language compatibility presents exciting opportunities for developers. Just like JRuby and Jython serve as examples of scripting languages that can run within Java, the goal is to simplify the implementation of new dynamic languages on the JVM and enhance their performance.
One practical advantage of this integration is utilizing JavaScript for scripting in Java games.
I hope this information proves helpful!