Writing Scripts in Nashorn - Scripting in Java: Integrating with Groovy and JavaScript - page 48

Chapter 4

Writing Scripts in Nashorn

In this chapter, you will learn:

• How to write scripts in Nashorn

• The difference between running the script in strict mode and

nonstrict mode

• How to declare variables and write comments

• Primitive and object data types, and how to convert values of one

data type to another data type

• Operators, statements, and creating and invoking functions in

Nashorn

• Different ways of creating and using objects

• Variable scoping and hoisting

• About built-in global objects and functions

Nashorn is a runtime implementation of the ECMAScript 5.1 specification on the
JVM. ECMAScript defines its own syntax and constructs for declaring variables, writing
statements, operators, creating and using objects, collections, iterating over collections of
data, and so on. Nashorn is 100 percent compliant with the ECMAScript 5.1, so you have
a new set of language syntax to learn when you work with Nashorn. For example, working
with objects in Nashorn is entirely different from working with objects in Java.
This chapter assumes that you have at least a beginner-level understanding of the
Java programming language. I will not explain details of the constructs and syntax offered
by Nashorn that work the same way as they work in Java. For example, I will not explain
what the assignment operator = in Nashorn does. Rather, I will simply mention that the
assignment operator = works the same in Nashorn and Java. The power of Nashorn is that
it lets you use Java libraries inside scripts. However, to use Java libraries inside Nashorn,
you must know the Nashorn syntax and constructs. This chapter gives you a brief
overview of Nashorn syntax and constructs.