Scripting language independent javax.script APIs like ScriptEngine.eval,
Bindings.get, Invocable.invokeFunction etc. translate undefined to null
(closest to what you'd expect in java world). But, nashorn specific APIs
like jdk.nashorn.api.scripting.JSObject.getMember/getSlot etc. return
undefined as undefined - without null translation. [as you're calling
nashorn engine specific API].
-Sundar
On 12/1/2016 1:13 AM, Art Fiedler wrote:
> @Sundararajan,
>
> I was previously using .getSlot(index) when extracting items from a
> ScriptObjectMirror when that mirror was an array until I ran into
> a undefined element and that is not equal to null as I had for my
> condition... so I swapped .getSlot(i) with .get(Integer.toString(i))
>
> Are getMember(), get(), and getSlot() suppose to all return the same null
> or undefined value? Or is it expected to have
> getMember() and getSlot() to return Undefined object and get() to return
> null?
>
> As a side note... If this is the intended behavior this might be a better
> way to get the Undefined object instead of making a
> call out of nashorn to a public static method.
>
> Here is an example... (jdk8 1.8.0_102)
>
> Thanks,
> Arthur Fiedler
>
>
> public static void main(String[] args) throws Exception {
> NashornScriptEngineFactory factory = new
> NashornScriptEngineFactory();
> ScriptEngine scriptEngine = factory.getScriptEngine();
> scriptEngine.eval("globalArray = ['line1',undefined,null];");
> ScriptObjectMirror array =
> (ScriptObjectMirror)scriptEngine.get("globalArray");
> System.out.println("size(): " + array.size());
> for(int i = 0; i < array.size(); i++) {
> System.out.println("Index: " + i);
> String iStr = String.valueOf(i);
> System.out.println(" GetMember('"+iStr+"'): " +
> array.getMember(iStr));
> System.out.println(" Get('"+iStr+"'): " + array.get(iStr));
> System.out.println(" GetSlot("+iStr+"): " +
> array.getSlot(i));
> }
> }
> /*
> size(): 3
> Index: 0
> GetMember('0'): line1
> Get('0'): line1
> GetSlot(0): line1
> Index: 1
> GetMember('1'): undefined
> Get('1'): null
> GetSlot(1): undefined
> Index: 2
> GetMember('2'): null
> Get('2'): null
> GetSlot(2): null
> */
