JavaScript module pattern: default values
design-patterns, javascript, module
Solution
There isn't much of a difference, it's really all about what's readable to you. I personally like the 2nd method because it separates the defaults from the logic.
Problem
I'm working on a project where we use a pattern to define "modules" (i.e. effectively public static classes), where each module has an `init()` that should be called once the module has been defined. It looks like: ``` MyNamespace.MyModule = (function () { var my = {}; my.init = function(config) { // setup initial state using config }; return my; })(); ``` I'm seeing two patterns in this code base for defining `config` defaults and wondering which one might be better—if there's any advantage or disadvantage that I'm not immediately seeing. Recommendations? Here's the first: ``` 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; })(); ```