title: vuejs filter is not a function error
body: <p>I've got a very basic array:</p>
  
  <pre><code>specialityTest: [{person:'nurse', text:'text1'}, 
  {person:'nurse', text:'text1'}, 
  {person:'physician', text:'text1'}, 
  {person:'physician', text:'text1'}]
  </code></pre>
  
  <p>I'm trying to filter this using basic filter function:</p>
  
  <pre><code>      this.specialityTest.filter((person) =&gt; {
          return (person =="physician")
        })
  </code></pre>
  
  <p>and then copy filtered array:</p>
  
  <pre><code>  methods: {
     seedSpeciality(){
        this.nurseListSpeciality2 = JSON.parse(JSON.stringify(this.specialityTest.filter(
        (person) =&gt; {
          return (person =="physician")
        })))
    },
   }
  </code></pre>
  
  <p>and this is not working for me... I've got error: </p>
  
  <p><code>Uncaught (in promise) TypeError: this.specialityTest.filter is not a function 
   at VueComponent.seedSpeciality (AddOfferDialog.vue?f4fc:1771)
      at VueComponent.boundFn [as seedSpeciality]</code>.</p>
  
  <p>What am I doing wrong here?</p>
  
  <p>edit:
  I run this function from api call:</p>
  
  <pre><code>  fetchSpecialityArray(){
      this.$http.get('http://127.0.0.1:8000/api/speciality')
        .then(response =&gt; response.json())
        .then(result =&gt; this.specialityTest = result).then(this.seedSpeciality.bind(this))
    },
  </code></pre>