SOURCE

new Vue({
  el: '#exercise',
  data: {
  },
  methods: {
  }
});

<script src="https://unpkg.com/vue/dist/vue.js"></script>

<div id="exercise">
  <!-- 1) Start the Effect with the Button. The Effect should alternate the "highlight" or "shrink" class on each new setInterval tick (attach respective class to the div with id "effect" below) -->
  <div>
    <button>Start Effect</button>
    <div id="effect"></div>
  </div>
  <!-- 2) Create a couple of CSS classes and attach them via the array syntax -->
  <div>I got no class :(</div>
  <!-- 3) Let the user enter a class (create some example classes) and attach it -->
  <br>
  <div>
    <input type="text">
    <div></div>
  </div>
  <!-- 4) Let the user enter a class and enter true/ false for another class (create some example classes) and attach the classes -->
  <div>
    <input type="text">
    <input type="text">
    <div></div>
  </div>
  <!-- 5) Repeat 3) but now with values for styles (instead of class names). Attach the respective styles.  -->
  <div>
    <input type="text">
    <div></div>
  </div>
  <!-- 6) Create a simple progress bar with setInterval and style bindings. Start it by hitting the below button. -->
  <div>
    <button>Start Progress</button>
  </div>
</div>

#effect {
  width: 100px;
  height: 100px;
  border: 1px solid black;
}

.highlight {
  background-color: red;
  width: 200px !important;
}

.shrink {
  background-color: gray;
  width: 50px !important;
}

.blue {
    background-color: blue;
}

.float {
    float: right;
}

.text-color {
    color: yellow;
}

.visible {
    width: 100px;
    height: 50px;
}

.progress-bar {
    width: 200px;
    height: 20px;
    border: 1px solid black;
}

.myClass2 {
    background-color: yellow;
    width: 150px;
    height: 150px;
}