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 Dec 20 '15 at 17:49 — OneCricketeer, Dec 20 '15 at 17:49

christopher clark · Answer 1 · 2015-12-20T17:12:57.917

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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 '15 at 17:12

answered Dec 20 '15 at 17:09

christopher clark

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You need to escape the quotes around Hi – OneCricketeer Dec 20 '15 at 17:11
can you please give link where i can see some examples/tutorials of using js in java – Narendra Jaggi Jan 02 '16 at 18:58

score 1 · Answer 2 · edited May 23 '17 at 12:32

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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 '17 at 12:32

Community

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answered Dec 20 '15 at 16:43

M Sach

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It is possible through scripting API, which OP is using: https://docs.oracle.com/javase/8/docs/technotes/guides/scripting/prog_guide/api.html – user3707125 Dec 20 '15 at 17:00
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 – Abhijit Desai Dec 21 '15 at 18:02

score 1 · Answer 3 · edited May 23 '17 at 11:51

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

score -2 · Answer 4 · answered Dec 20 '15 at 17:16

-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 '15 at 17:16

Akhil Menon

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I mean it's no different than calling powershell functions with .Net. Or Sql statements... – christopher clark Dec 20 '15 at 19:33
Serverside scripting is an elegant thing and can even be sophisticated architecture – Marged Jan 02 '16 at 20:30

calling javaScript from java method

4 Answers4