Object.keys function in JS file that runs from Java

Question

When I try to use Object.keys function in JavaScript file that runs as Java application I get Exception.

I want to use some function from JS file like this:

    function calculateProductPrice(orderData)
    {
        ...
        k = Object.keys(prices);    
        for (var i = k.length; i > -1; i--)
        {
            ...
        }       
        ...     
    }

    var prices = {
             "1":[
                99,
                106,
                113,
               ...

Fragment of java code that use this script:

Context context = Context.enter();
ScriptableObject  scope = context.initStandardObjects();
FileReader fr = new FileReader("script.js");
context.evaluateReader(scope, fr, "<cmd>", 1, null);
Object orderData = Context.javaToJS(new OrderData(), scope);
scope.put("orderData", scope, orderData);
Object result = context.evaluateString(scope, "calculateProductPrice(orderData)", "<cmd>", 1, null);

And I get Exception:

Exception in thread "main" org.mozilla.javascript.EcmaError: TypeError: Cannot find function keys in object function Object() { [native code for Object.Object, arity=1] }
. (<cmd>#11)
    at org.mozilla.javascript.ScriptRuntime.constructError(ScriptRuntime.java:3654)
    at org.mozilla.javascript.ScriptRuntime.constructError(ScriptRuntime.java:3632)
    at org.mozilla.javascript.ScriptRuntime.typeError(ScriptRuntime.java:3660)
    at org.mozilla.javascript.ScriptRuntime.typeError2(ScriptRuntime.java:3679)
    at org.mozilla.javascript.ScriptRuntime.notFunctionError(ScriptRuntime.java:3743)
    at org.mozilla.javascript.ScriptRuntime.getPropFunctionAndThisHelper(ScriptRuntime.java:2247)
    at org.mozilla.javascript.ScriptRuntime.getPropFunctionAndThis(ScriptRuntime.java:2214)
    at org.mozilla.javascript.gen.c1._c1(<cmd>:11)
    at org.mozilla.javascript.gen.c1.call(<cmd>)
    at org.mozilla.javascript.optimizer.OptRuntime.callName(OptRuntime.java:97)
    at org.mozilla.javascript.gen.c2._c0(<cmd>:1)
    at org.mozilla.javascript.gen.c2.call(<cmd>)
    at org.mozilla.javascript.ContextFactory.doTopCall(ContextFactory.java:398)
    at org.mozilla.javascript.ScriptRuntime.doTopCall(ScriptRuntime.java:3065)
    at org.mozilla.javascript.gen.c2.call(<cmd>)
    at org.mozilla.javascript.gen.c2.exec(<cmd>)
    at org.mozilla.javascript.Context.evaluateString(Context.java:1104)
    at net.terraincognita.restapi.service.ScriptEngine.<init>(ScriptEngine.java:65)
    at net.terraincognita.restapi.service.ScriptEngine.main(ScriptEngine.java:94)
Java Result: 1

Answer 1

This method is not defined for the Object class in Rhino.

The Rhino documentation states:

Rhino contains

• All the features of JavaScript 1.7

The Mozilla JavaScript documentation states Object.keys was:

Introduced in JavaScript 1.8.5

The same Object.keys documentation includes an example of how to add this to previous version of JavaScript.

Answer 2

Object.keys() is an ECMAScript 5 feature introduced in Javascript 1.8.5.

Rhino, on the other hand, is based on Javascript 1.7.

So, unfortunately, you're stuck with:

for (var i in prices) {
  if (prices.hasOwnProperty(i)) {
    // do stuff
  }
}