title: className not working in VueJS method
body: <p>I want to change the classNames of all elements with the class on "link". I am using a method which is called via a click action on the element. I tested out getting a length from the function and that works fine but adding a class does not. Anyone know why?</p>
  
  <p><strong>HTML</strong></p>
  
  <pre><code>&lt;div id="app"&gt;
    &lt;ul&gt;
      &lt;li&gt;&lt;a href="#" class="link" @click="myFunc"&gt;Link text 1&lt;/a&gt;&lt;/li&gt;
      &lt;li&gt;&lt;a href="#" class="link" @click="myFunc"&gt;Link text 2&lt;/a&gt;&lt;/li&gt;
      &lt;li&gt;&lt;a href="#" class="link" @click="myFunc"&gt;Link text 3&lt;/a&gt;&lt;/li&gt;
    &lt;/ul&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p><strong>JS</strong></p>
  
  <pre><code>var app = new Vue({
  el: '#app',
  methods: {
    myFunc: function(event){
  
        // works
        var ElLength = document.getElementsByClassName('link').length;
        console.log('ElLength = ' + ElLength);
  
        // does not work
        document.getElementsByClassName('link').className += " hullaballoo";
  
      }
    }
  });
  </code></pre>
  
  <p><strong><a href="https://jsfiddle.net/kf0vwtgs/" rel="nofollow noreferrer">JSFIDDLE</a></strong></p>