lodash: _.objectMap

_.objectMap.js

/**
 * Creates an object where each property is composed from
 * an element of keys (key) and the value from callback(key).
 *
 * @param  {array} keys The array of keys.
 * @param  {function} [callback=_.identity] The callback(key) that returns the object:s values.
 * @return {object} Returns an object composed of the given keys and callback(key) for values.
 */
_.objectMap = function(keys, callback) {
  callback = callback || _.identity;
  var object = {};
  for(var index = 0, len = keys.length; index < len; ++index) {
    var key = keys[index];
    object[key] = callback(key);
  }
  return object;
};

// In other words:
_.objectMap = function(array, func) {
	return _.object(array, _.map(array, func));
};

// An example
var config = _.objectMap(['package', 'colors', 'external', 'languages'], function(file) {
	return grunt.file.readJSON(file + '.json');
});