title: How to check if array contains a value in Javascript
body: <p>I have a json object which has an array property 'partners' like below:</p>
  
  <pre><code>    { 
      "_id" : ObjectId("578667b1bb14ca1c2773adaa"), 
      "customer" : null,  
      "created" : ISODate("2016-07-13T16:09:21.015+0000"), 
      "description" : "", 
      "subject" : "case 2", 
      "__v" : NumberInt(5), 
      "partners" : [
          ObjectId("57857d93038aacd81ef3ad55"), 
          ObjectId("57857d93038aacd81ef3ad56")
      ]
  }
  </code></pre>
  
  <p>I would like to check if an element already exists on the partner array using the following code:</p>
  
  <pre><code> _.includes(case_.partners, partner._id)
  </code></pre>
  
  <p>Just so u know I am using lodash for this but for some reason is not working and I have no clue why, anyone knows what is the problem here?</p>