Function afterMount

docs/examples/counter/index.js:24–29

(component, el, setState)

  },

  afterMount (component, el, setState) {
    let counter = 0;
    intervals[component.id] = setInterval(() => {
       setState({ secondsElapsed: counter++ })
    }, 1000);
  },

  beforeUnmount (component) {
    clearInterval(intervals[component.id]);