Vue

HTML

<div id="app">
<b>{{count}}</b>
<button @click="activate">activate</button>
<button @click="stop">stop</button>
</div>

Vue

new Vue({
  el: "#app",
  data: {
    count: 0,
    repeat: null
  },
  methods: {
  	activate () {
      this.repeat = setInterval(() => this.count++, 1000)
    },
    stop () {
      clearInterval(this.repeat)
    }
  }
})