Nashorn

Learn about nashorn, javascripting in java8

1. NASHORN
JavaScripting in Java8
Presentation by,
Hina Firdaus
M.tech(CSE)
2
nd
Semester
Guided by,
Dr. Syed Imtiyaz Hassan
Assistant Professor
SEST

2. Index
What is Nashorn?
Why is Nashorn?
Features of Nashorn.
Shortcomings of Nashorn.
Jjs.
Summary.

4. What is Nashorn?
Nashorn is replacement introduced with Java 8 for the old, slow
Rhino JavaScript engine.
It is based on the Da Vinci Machine (JSR 292/javax.script) and has
been released with Java 8
The project aim will be to allow embedding JavaScript in Java
applications via JSR-223 and to develop standalone JavaScript
applications.
Nashorn comprises of an embedded JavaScript interpreter and a
command line tool.
Nashorn, pronounced
"nass-horn," is German
for "rhinoceros," and it's
one of the animal names
for a German tank
destroyer used in World
War II.

6. Why Nashorn?
Nashorn scripts do not need to be compiled. Nashorn fully supports
ECMAScript 5.1 specification along with some extensions, to 100% pure Java
implementation and 100% complied to bytecode and not the interpreted
mode as with Rhino.
Nashorn provides much better performance than Rhino engine.
It directly compiles the JavaScript code in-memory and passes the Java
bytecode to the JVM, and uses invokedynamic which provides backward
compatibility to JDK7.
Nashorn provides a flexibility to the users that they can either
programmatically use it from Java programs or they can utilize it from the
command line tool “jjs” which is located in “$JAVA_HOME/bin” directory.
It provides much faster execution and multi-threading of JavaScript while
running in Java’s JRE.
Nashron can help in executing the OS level commands very easily.
So far no security risk or exposure has been identified with Nashorn.

7. Features of Nashorn.
Interoperable:
Nashorn provides interoperability between the Java and
JavaScript i.e., Java code can call JavaScript code, and vice
versa.
Embeddable:
It’s very easy to use Nashorn to extend your Java applications
with JavaScript code as there are no third party libraries required
to add on.
Compatible
The goal pursued by the Nashorn team is not to provide a fast
JavaScript implementation for a specific browser - it’s to provide
a very fast implementation for server-side JavaScript
applications and scripts embedded in Java applications.

8. Continue…
Performant
Nashorn uses the invokedynamic JVM instruction to implement
all of its invocations. That is a major component of the
comparative improvement of performance and memory usage
regarding Mozilla Rhino.
Shell Scripting
Nashorn provides several built-in functions to exit the script, print
and read lines from standard output and input, read files, load
scripts, and bind properties of objects.
JavaFX
User can write JavaFX applications entirely in JavaScript using
Nashorn.

9. Shortcomings of Nashorn.
Nashorn will only support ECMAScript-262 Edition 5.1. It will not
support any features of Edition 6 or any nonstandard features
provided by other JavaScript implementations.
Nashorn will not include a browser plug-in API.
Nashorn will not include support for DOM/CSS or any related
libraries (such as jQuery, Prototype, or Dojo).
Nashorn will not include direct debugging support.

10. jjs
For Nashorn engine, JAVA 8 introduces a new command line tool, jjs to
execute java script code at console.
Steps to create and execute jjs script:
Step 1: Interpreting js file.
Step 2: jjs in interactive mode
Step 3: pass arguments
Step 4: Calling JavaScript in JAVA
Using ScriptEngineManager, JavaScript code can be called and interpretted in java.
Step 5: Verify the result.
Step 6: Calling Java from JavaScript

11. Summary
Project Nashorn has enhanced the original JDK 6 Rhino
implementation by greatly improving performance for longer running
applications, for example when used inside a web server.
It provides a timely update of performance and capabilities of the
co-bundled JavaScript engine.