Arguments / named params polymorph

getConfig

    /**
     * The user can pass in the formal parameters, or a named
     * parameters object in the first argument. Either way,
     * we need to initialize the variables to the expected
     * values.
     * 
     * @param {String} optionNames Parameter names.
     * 
     * @return {object} New configuration object.
     */
    getConfig = function getConfig(optionNames) {
      var config = {}, // New config object
        // Comma separated string to Array
        optionNames = optionNames.split(','),
        // Turn arguments into array, starting at index 1
        args = [].slice.call(arguments, 1);

      optionNames.forEach(function (optionName, index) {
        // Strip whitespace
        optionName = optionName.trim();
        // Use first argument as params object if it exists...
        config[optionName] = args[0][optionName]
          || args[index]; // or grab the formal parameter.
      });

      return config;
    };

This even allows you to mix and match both approaches, which I have found useful already.