Object property values lost on server side when ob

Question

Preface

I am posting this to warn others of a potential bug in google.script.run, to present a possible work-around, and to solicit further community insights into what might be going on.

The Problem

I am passing a large data object to a server-side function invoked via google.script.run. Here is it what it looks like on the client-side before the call to Google.script.run (obtained by JSON.stringify'ing and outputting through an alert box):

{"roundStartTime":"12:00:00","roundFinishTime":"12:45:23","holeData":{"1":{"strokes":1,"finishTime":"12:02:00"},"2":{"strokes":6,"finishTime":"12:04:00"},"3":{"strokes":7,"finishTime":"12:06:00"},"4":{"strokes":8,"finishTime":"12:08:00"},"5":{"strokes":9,"finishTime":"12:10:00"},"6":{"strokes":10,"finishTime":"12:12:00"},"7":{"strokes":11,"finishTime":"12:14:00"},"8":{"strokes":12,"finishTime":"12:16:00"},"9":{"strokes":13,"finishTime":"12:18:00"},"10":{"strokes":1,"finishTime":"12:30:00"},"11":{"strokes":11,"finishTime":"12:33:00"},"12":{"strokes":8,"finishTime":"12:35:00"},"13":{"strokes":3,"finishTime":"12:37:00"},"14":{"strokes":7,"finishTime":"12:39:00"},"15":{"strokes":10,"finishTime":"12:40:00"},"16":{"strokes":11,"finishTime":"12:42:00"},"17":{"strokes":13,"finishTime":"12:45:00"},"18":{"strokes":6}}}`

And here's the same object as it is received on the server-side (obtained by JSON.stringify'ing and outputting through Google's Logger.log function):

{"roundStartTime":"12:00:00","holeData":{"11":{"strokes":11,"finishTime":"12:33:00"},"12":{"strokes":8,"finishTime":"12:35:00"},"13":{"strokes":3,"finishTime":"12:37:00"},"14":{"strokes":7,"finishTime":"12:39:00"},"15":{"strokes":10,"finishTime":"12:40:00"},"16":{"strokes":11,"finishTime":"12:42:00"},"17":{"strokes":13,"finishTime":"12:45:00"},"18":{"strokes":6,"finishTime":null},"1":{"strokes":1,"finishTime":"12:02:00"},"2":{"strokes":6,"finishTime":"12:04:00"},"3":{"strokes":7,"finishTime":"12:06:00"},"4":{"strokes":8,"finishTime":"12:08:00"},"5":{"strokes":9,"finishTime":"12:10:00"},"6":{"strokes":10,"finishTime":"12:12:00"},"7":{"strokes":11,"finishTime":"12:14:00"},"8":{"strokes":12,"finishTime":"12:16:00"},"9":{"strokes":13,"finishTime":"12:18:00"},"10":{"strokes":1,"finishTime":"12:30:00"}}."roundFinishTime":"12:45:23"}

As you can see, the object appears to be identical, except that the properties of "holeData" appear in a different order on the server-side. The problem is NOT that object properties are ordered differently, however; it is that I simply can't access properties on the server side. Please read on for more details.

On the server side, I can confirm that the holeData property has the following (sub)properties by JSON.stringify'ing a call to Object.keys(data.holeData):

["11","12","13","14","15","16","17","18","1","2","3","4","5","6","7","8","9","10"]

However, When I then attempt to access the "strokes" (sub)property of any one of these objects, e.g.:

data.holeData["1"].strokes --or-- data.holeData["1"]["strokes"], I get an error:

Execution failed: TypeError: Cannot read property "strokes" from undefined.

So something unexpected happened to the object when it was transferred from the client to the server side.

Note: I have carefully read the rules for legal parameters to google.script.run functions, and my object does not appear to violate any of them. It's composed solely of string and integer data.

The Solution

I have fixed the issue by applying JSON.stringify() to the object on the client side, and then JSON.parse() on the server-side. When I serialize/deserialize in this way, I am able to access all object properties on the server-side.

Any idea what is happening with this object? Is this a bug or a feature?