Passing parameters to a javascript function

Question

So here's the deal: I read this article and started trying to use Rhino. So far I got how to invoke a function, and how to get its return. What I can't do is pass the function's parameter. Here's my code:

ScriptEngineManager engineMgr = new ScriptEngineManager();
ScriptEngine engine = engineMgr.getEngineByName("ECMAScript");

String js = "";
js += "function add(a, b) {";
js += " var sum = parseFloat(a) + parseFloat(b);";
js += " println(sum);";
js += "}";

engine.put("a", 3);
engine.put("b", 5);

Object returnn = null;
try {
    engine.eval(js);

    Invocable invocableEngine = (Invocable) engine;
    returnn = invocableEngine.invokeFunction("add");
} catch (ScriptException e) {
    System.out.println("Script error.");
} catch (NoSuchMethodException e) {
    System.out.println("Method error.");
}

System.out.println(returnn);

I get no Exception whatsoever, but the return comes back as NaN. I tried printing a and b (The parameters) and they always come as null. If this is not the best way to invoke a function, please just point me to some useful thread. (Which I did not find on my own)

TYVM in advance

You can get rid of the .put calls. And instead call invokeFunction("add", 3, 5) — skarmats
– skarmats, Commented May 21, 2012 at 11:44
It worked. Than you! But if I can ask something else.. I won't always know how many parameters the method has. Any suggestions on how to solve this? — Igor Brusamolin Lobo Santos
– Igor Brusamolin Lobo Santos, Commented May 21, 2012 at 11:54
In JavaScript you mean? Check this link: stackoverflow.com/questions/4138012/… — sproketboy
– sproketboy, Commented May 21, 2012 at 11:59
Btw, if you want to get a return value you'll need to have a return sum; statement in your JavaScript function definition. The return value will appear as return value of invokeFunction and needs to be cast (double) or sth. — skarmats
– skarmats, Commented May 21, 2012 at 12:04

rjdkolb · Accepted Answer · 2017-07-14 03:59:34Z

2

This works for me:

Object params[] = {1,2,3};
Invocable invocable = (Invocable) script.getEngine();
invocable.invokeFunction("myFunction", params);

edited Jul 14, 2017 at 3:59

rjdkolb

12.1k13 gold badges79 silver badges94 bronze badges

answered May 21, 2012 at 11:53

sproketboy

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1 Comment

skarmats Over a year ago

invocable.invocableEngine should probably be invocableEngine.invokeFunction

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