Java 8 Nashorn load script without executing it

Question

I am using Java 8 Nashorn to execute a specific previously agreeed upon method. I could Invoke the specific method no problem. One thing that bugged me though is that when I load the script, it also executes it.

For example if file.js contains a print("hello world!") the scriptEngine.eval(new FileReader("./file.js") would execute and print hello world. I have to do this before I could invoke the specific method I want.

Is there a way to eval()/load the scripts without executing it?

Thanks

"Is there a way to load the scripts without executing it?" What would be the result of this operation? Do you just want to get the source text? In that case, just read the file with FileReader? — Felix Kling
– Felix Kling, Commented Mar 17, 2016 at 22:56
I wanted to eventually Invoke a specific method, but I am unable to do that without previously calling .eval() which executes the script :( — user3808203
– user3808203, Commented Mar 17, 2016 at 23:08

user3808203 · Accepted Answer · 2016-03-19 22:21:34Z

2

turns out You could do this by Casting engine to Compilable then call the compile function.

final ScriptEngine engine = new ScriptEngineManager().getEngineByName("nashorn");
final Compilable compilable = (Compilable) engine;
        final Invocable invocable = (Invocable) engine;
        final String statement = "function fetch(values) { return values['first_name'] + ' ' + values['last_name']; };";
        final CompiledScript compiled = compilable.compile(statement);

This achieved what I want without needing to eval() it

answered Mar 19, 2016 at 22:21

user3808203

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