index.js

var type = require('component-type');
var clone = require('component-clone');


/**
 * Expose `alias`.
 */

module.exports = alias;


/**
 * Alias an `object`.
 *
 * @param {Object} obj
 * @param {Mixed} method
 */

function alias (obj, method) {
  switch (type(method)) {
    case 'object': return aliasByDictionary(clone(obj), method);
    case 'function': return aliasByFunction(clone(obj), method);
  }
}


/**
 * Convert the keys in an `obj` using a dictionary of `aliases`.
 *
 * @param {Object} obj
 * @param {Object} aliases
 */

function aliasByDictionary (obj, aliases) {
  for (var key in aliases) {
    if (undefined === obj[key]) continue;
    obj[aliases[key]] = obj[key];
    delete obj[key];
  }
  return obj;
}


/**
 * Convert the keys in an `obj` using a `convert` function.
 *
 * @param {Object} obj
 * @param {Function} convert
 */

function aliasByFunction (obj, convert) {
  // have to create another object so that ie8 won't infinite loop on keys
  var output = {};
  for (var key in obj) output[convert(key)] = obj[key];
  return output;
}