title: Linq JS join syntax
body: <p>I am trying to join an array of dates and values to an array of dates, without filtering out the extra dates. The LinqJS reference <a href="http://neue.cc/reference.htm" rel="nofollow noreferrer">here</a> is pretty confusing on how I would actually go about using the join. The question <a href="https://stackoverflow.com/questions/22671667/inner-join-with-linqjs">here</a> did not help much either.</p>
  
  <p><strong>Edit</strong>:</p>
  
  <p>Join documentation here: <a href="https://svschmidt.github.io/linqjs/Collection.html#Join" rel="nofollow noreferrer">https://svschmidt.github.io/linqjs/Collection.html#Join</a></p>
  
  <p>It looks like I need help sorting out how to get the join to be an <code>outer</code> and not an <code>inner</code> join so it includes null/undefined values.</p>
  
  <p>Say I have two arrays:</p>
  
  <p><strong>Array 1:</strong></p>
  
  <pre><code>[
  '2017-02-10',
  '2017-02-11',
  '2017-02-12',
  '2017-02-13',
  '2017-02-20',
  '2017-02-21',
  '2017-02-22',
  '2017-02-23',
  '2017-02-24',
  '2017-02-25',
  '2017-02-26',
  '2017-02-27'
  ]
  </code></pre>
  
  <p><strong>Array 2:</strong></p>
  
  <pre><code>[
    { date: '2017-02-10', value:  5 },
    { date: '2017-02-12', value:  8 },
    { date: '2017-02-13', value: 13 },
    { date: '2017-02-21', value: 14 },
    { date: '2017-02-24', value: 11 },
    { date: '2017-02-27', value:  7 }
  ]
  </code></pre>
  
  <p>I want to join them so I get this as my result (<code>-</code> for <code>undefined</code>):</p>
  
  <pre><code>[
  '5',
  -,
  '8',
  '13',
  -,
  '14',
  -,
  -,
  '11',
  -,
  -,
  '7'
  ]
  </code></pre>
  
  <p>My current syntax: </p>
  
  <pre><code>Enumerable.from(array1).join(array2, '$', '$.date', "outer, inner =&gt; inner.value").toArray()
  </code></pre>
  
  <p>This results in an array of the values, but the results are still inner joined, and it filters out what might be the <code>null/undefined</code> items.</p>
  
  <p>How can I do this? How does the join syntax work for LinqJS?</p>