title: lodash merge one object
body: <p>I want to use lodash to manipulate and formate a JSON object. 
  After several (parallel) functions, I get a Object like this (the Object is the result of all parallel tasks):</p>
  
  <pre><code> obj: [ { id: '1',
      count: 100 },
    { id: '2',
      count: 50 },
    { id: '3',
      count: 10 },
    { id: '1',
      type: A},
    { id: '2',
      type: B },
    { id: '3',
      type: C },
    { id: '1',
      other: no },
    { id: '2',
      other: no},
    { id: '3',
      other: yes},
    { input: 'key',
      output: 'screen',
      match: 'no',
      id: '1' },
    { input: 'key',
      output: 'screen',
      match: 'yes',
      id: '2' },
    { buy: '100',
      id: '1' },
    { buy: '200',
      id: '3' } ]
  </code></pre>
  
  <p>My Output should combine the object, group By the id. Like that:</p>
  
  <pre><code> [ { id: '1',
      count: '',
      other: '',
      input: '',
      output: '',
      match: '',
      buy: ''},
   { id: '2',
      count: '',
      other: '',
      input: '',
      output: '',
      match: '',
      buy: ''},
    { id: '3',
      count: '',
      other: '',
      input: '',
      output: '',
      match: '',
      buy: ''} ]
  </code></pre>
  
  <p>My attempt to achiev this, is to group by id and map it. So I create a new object and chain lodash functions.</p>
  
  <pre><code>var result=_(obj)
             .groupBy('id')
             .map((objs, key) =&gt; ({
                 'id': key,
                 'count': (_.map(objs, 'count')),
                 'other': (_.map(objs, 'other')),
                 'input': (_.map(objs, 'input')),
                 'output': (_.map(objs, 'output')),
                 'match': (_.map(objs, 'match')),
                 'buy': (_.map(objs, 'buy')),
    }))
    .value();
  </code></pre>
  
  <p>The id field is correct but all other fields are bad.</p>
  
  <p>for example the count field (id= 1):</p>
  
  <blockquote>
    <p>[ 100, undefined, undefined ]</p>
  </blockquote>
  
  <p>count field (id= 2):</p>
  
  <blockquote>
    <p>[ undefined, 50, undefined ]</p>
  </blockquote>
  
  <p>What should I do? </p>