Method key

rhino/src/main/java/org/mozilla/javascript/NativeMap.java:285–294

Extracts the key from the first args entry if any and takes care of the Delegator. This is used by NativeSet, NativeWeakMap, and NativeWekSet also. @param args the args @return the first argument (de-delegated) or undefined if there is no element in args

(Object[] args)

     * @return the first argument (de-delegated) or undefined if there is no element in args
     */
    static Object key(Object[] args) {
        if (args.length > 0) {
            Object key = args[0];
            if (key instanceof Delegator) {
                return ((Delegator) key).getDelegee();
            }
            return key;
        }
        return Undefined.instance;
    }
}