Writing Scripts in Nashorn - Scripting in Java: Integrating with Groovy and JavaScript - page 76

■ Tip the index in the for...in statement is of String type, not number type.

The for..each..in statement is not in the ECMAScript 5.1 specification. The
Mozilla JavaScript 1.6 extension that is supported by Nashorn. As the for..in statement
iterates over the indices/property names of a collection, the for..each..in statement
iterates over the values in the collection. It works in the same way as the for-each
statement in Java. Notice that a set is a collection of unique values without giving names
to the values. You cannot iterate over a set using the for..in statement, but you can do so
using a for..each..in statement. Its syntax is:

for(var value in object)
Statement;

The following code shows how to use a for..each..in statement to iterate over the
elements (not indices) of an array:

// Create an array of three strings
var empNames = ["Ken", "Fred", "Li"];

// Use the for..each..in statement to iterate over elements of the array
for each(var empName in empNames) {
printf(empName);
}

Ken
Fred
Li

I will discuss more about the for..in and for..each..in statements in Chapter 7.

The continue, break, and return Statements
The continue , break , and return statements in Nashorn works the same as in Java. The
continue and break statements can be labelled. The continue statement skips the rest of
the body of the iteration statement and jumps to the beginning of the iteration statement
to continue with the next iteration. The break statement jumps to the end of the iteration
and switch statement in which it appears. The return statement in a function returns the
control to the caller of the function. Optionally, the return statement can also return a
value to the caller.