JavaScript Module Pattern: Default Values

I am working on a project in which we use a template to define "modules" (ie effectively public static classes) where each module has init()

to be called after the module has been defined. It looks like this:

MyNamespace.MyModule = (function () {
    var my = {};
    my.init = function(config) {
        // setup initial state using config
    };
    return my;
})();

      

        
        
        
      

    

I see two patterns in this codebase for the config

default definition and wonder which one might be better - if there are any advantages or disadvantages that I don't see right away. Recommendations?

Here's the first one:

MyNamespace.MyModule = (function () {
    var my = {}, 
        username,
        policyId,
        displayRows;

    my.init = function(config) {
        config = config || {};
        username = config.username || 'Anonymous';
        policyId = config.policyId || null;
        displayRows = config.displayRows || 50;
    };

    return my;
})();

      

        
        
        
      

    

And here's the second:

MyNamespace.MyModule = (function () {
    var my = {}, 
        username = 'Anonymous',
        policyId = null,
        displayRows = 50;

    my.init = function(config) {
        config = config || {};
        username = config.username || username;
        policyId = config.policyId || policyId;
        displayRows = config.displayRows || displayRows;
    };

    return my;
})();