calling javaScript from java method

Question

I want to execute JavaScript function from Java. I used the following piece of code

ScriptEngineManager manager = new ScriptEngineManager();    
ScriptEngine engine = manager.getEngineByName("JavaScript");

but this throws an exception for the alert() method ?

engine.eval("alert('HI');");

Try eval("alert(\"HI\")");

OneCricketeer
– OneCricketeer

2015-12-20 17:49:17 +00:00
Commented Dec 20, 2015 at 17:49 — OneCricketeer
– OneCricketeer, Commented Dec 20, 2015 at 17:49

christopher clark · Accepted Answer · 2015-12-20 17:12:57Z

2

So. I'm pretty sure your code here is incorrect.

engine.eval("alert(HI);");

Try.

engine.eval("alert('Hi');");

unless you have a variable HI declared.

edited Dec 20, 2015 at 17:12

answered Dec 20, 2015 at 17:09

christopher clark

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2 Comments

OneCricketeer Over a year ago

You need to escape the quotes around Hi

Narendra Jaggi Over a year ago

can you please give link where i can see some examples/tutorials of using js in java

Community · Accepted Answer · 2017-05-23 12:32:49Z

1

you can not call javascript from java in any way. javascript is client side language and executed on browser where as java is executed on server

Update :- Thanks guys i learnt something new here.

when i execute the code in op i get below error

Error executing script: ReferenceError: "alert" is not defined in <eval> at line number 1

Reason is alert is not part of JavaScript, it's part of the window object provided by web browsers.so, Nashhorn javascript engine does not know about it.

Please see ReferenceError: "alert" is not defined

edited May 23, 2017 at 12:32

CommunityBot

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answered Dec 20, 2015 at 16:43

M Sach

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2 Comments

user3707125 Over a year ago

It is possible through scripting API, which OP is using: docs.oracle.com/javase/8/docs/technotes/guides/scripting/…

Abhijit Desai Over a year ago

with help of scripting api we can able to call basic javascript but we cant use any predefined method it will throws an exception so if you know any other solution please provide user3707125

Community · Accepted Answer · 2017-05-23 11:51:38Z

1

It appears that "alert()" is part of the window object provided by web browsers. it doesn't exist here

I have modified java code:

ScriptEngineManager manager = new ScriptEngineManager();      
ScriptEngine engine  = manager.getEngineByName("JavaScript");
engine.eval("print('HI');");

This is useful: Java Scripting Programmer's Guide
Information about javscript window object: The Window Object

edited May 23, 2017 at 11:51

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answered Jan 2, 2016 at 18:26

Tornike Shavishvili

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Comments

Akhil Menon · Accepted Answer · 2015-12-20 17:16:29Z

-2

You are doing it the wrong way, you cannot call JavaScript function from java code because one is executed at client side and other at server side...even if you achieve that using some API it's wrong way of architecturing of code.

answered Dec 20, 2015 at 17:16

Akhil Menon

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2 Comments

christopher clark Over a year ago

I mean it's no different than calling powershell functions with .Net. Or Sql statements...

Marged Over a year ago

Serverside scripting is an elegant thing and can even be sophisticated architecture

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