Set a default parameter value for a JavaScript function

defaults.js

// http://stackoverflow.com/questions/894860/set-a-default-parameter-value-for-a-javascript-function
// There are a lot of ways, but this is my preferred method
// it lets you pass in anything you want, including false or null.
// (typeof null == "object")

function foo(a, b){
  a = typeof a !== 'undefined' ? a : 42;
  b = typeof b !== 'undefined' ? b : 'default_b';
  ...
}