Question

Here’s what I’ve run into…
I design my object:

var Tab = function () {
    var _data = [], _owners = [], _supportWorkers = [], _watchers = [];
        var _dataLength = function () { return _data.length; };
    return {
        Data: _data,
        Owners: _owners,
        SupportWorkers: _supportWorkers,
        Watchers: _watchers,
            Length: _dataLength
    };
};

var newObject = new Tab();
newObject.Data = [{"my":"data"}];
alert(newObject.Length()); // Length == 0
alert(newObject.Data.length);​ // Length == 1 

This obviously changes the reference, but does not change the reference INSIDE the object. Is creating a Getter/Setter function the only way to avoid this from happening?

Answer 1

var _dataLength = function () { return this.Data.length; };

Will work from the outside, since this will refer to the instance. It will not work from within the module itself.

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Here’s how I would do it – the revealing module pattern is pointless if all your data is revealed:

var Tab = function () { 
    this.data = [];
    this.owners = [];
    this.supportWorkers = [];
    this.watchers = [];
}
Tab.prototype.dataLength = function () { return this.data.length; };