defaults
A simple one level options merge utility
install
npm install defaults
use
var defaults = require('defaults');
var handle = function(options, fn) {
  options = defaults(options, {
    timeout: 100
  });
  setTimeout(function() {
    fn(options);
  }, options.timeout);
}
handle({ timeout: 1000 }, function() {
  // we're here 1000 ms later
});
handle({ timeout: 10000 }, function() {
  // we're here 10s later
});
summary
this module exports a function that takes 2 arguments: options and defaults.  When called, it overrides all of undefined properties in options with the clones of properties defined in defaults
Sidecases: if called with a falsy options value, options will be initialized to a new object before being merged onto.
