console.log('parts version is ' + parts.VERSION);

​

// console.log(parts.merge)

​

const {

  merge, isUndefined, isArray,

} = parts;

​

const hira = {

  'dog': 'いぬ',

  'cat': ['ねこ'],

  'human': 'ひと',

}

const kana = {

  'dog': ['イヌ'],

  'cat': ['ネコ', 'ニャンコ'],

}

const kan = {

  'dog': [],

  'cat': '猫',

  'human': '人',

  'car' : '車',

}

​

const result = merge([hira, kana, kan], (value, target, key) => {

  if (!isArray(value)) {

    value = [value];

  }

  if (isUndefined(target)) {

    return value

  }

  for (const v of value) {

    target.push(v);  

  }

  return target;

});

​

console.log(result);