Vue

HTML

<div id="app">
  <div>
      {{time}}
  </div>
  <div>
      {{value}}
  </div>
</div>

CSS

body {
  background: #20262E;
  padding: 20px;
  font-family: Helvetica;
}

#app {
  background: #fff;
  border-radius: 4px;
  padding: 20px;
  transition: all 0.2s;
}

li {
  margin: 8px 0;
}

h2 {
  font-weight: bold;
  margin-bottom: 15px;
}

del {
  color: rgba(0, 0, 0, 0.3);
}

Vue

new Vue({
  el: "#app",
  data: {
    value:"test",
    time:0
  },
  mounted: function(){
    let t0 = performance.now();                 
    this.value = this.findPrimes(51475143);
    let t1 = performance.now();
    this.time = t1 - t0;
  },
  methods: {
    findPrimes(max){
       let dont = [], primes = [];
       for (var i = 2; i <= max; i++) {
         if (!dont[i]) {
           primes.push(i);
           for (var j = i; j <= max; j += i) dont[j] = true;
         }
       }
    }
  }
})