Object flatten

obj-flatten.js

/**
 * Object flattener
 * http://stackoverflow.com/questions/19098797/fastest-way-to-flatten-un-flatten-nested-json-objects
 *
 * @param {Object} obj to flatten
 * @return {Object} flattened obj
 */

function flatten(data) {
  var result = {}
    , isEmpty, prop, i, len
  
  function recurse (current, path) {
    if (Object(current) !== current) {
      return result[path] = current
    } 
    if (Array.isArray(current)) {
      for (i = 0, len = current.length; i < len; i++) {
        recurse(current[i], path + '[' + i + ']')
      }
      if (len == 0) {
        result[path] = []
      }
      return
    }
    isEmpty = true
    for (prop in current) {
      isEmpty = false;
      recurse(current[prop], path ? path + '.' + prop : prop)
    }
    if (isEmpty && path) {
      result[path] = {}
    }
  }
  recurse(data, '')
  return result
}