JavaScript in Java

How to use javascript in java apps?

There an example:
// create a script engine manager
ScriptEngineManager factory = new ScriptEngineManager();
// create a JavaScript engine
ScriptEngine engine = factory.getEngineByName("JavaScript");
// evaluate JavaScript code from String
Double obj = (Double)engine.eval("10.53*25.73/43.57"); // Any javascript command

I use this solution in scrape application where some of values were as math expression.