index.html

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .count {
      cursor: pointer;
    }
  </style>
</head>

<body>
  <div id="app"></div>
  <script type="module">
    import { h, reactive, watchEffect, mount, patch } from './dist/mini-vue.esm.js'
    const App = {
      data: reactive({
        count: 0
      }),
      render() {
        return h('div', {
          class: 'count',
          style: 'color:red;',
          onClick: () => {
            this.data.count++
            const count = document.querySelector('.count')
            if (Math.abs(this.data.count) % 2 === 0) {
              count.style.color = 'blue'
            } else {
              count.style.color = 'red'
            }
          }
        }, String(this.data.count))
      }
    }

    function mountApp(component, container) {
      let isMounted = false
      let prevVom;

      watchEffect(() => {
        if (!isMounted) {
          prevVom = component.render()
          mount(prevVom, container)
          isMounted = true
        } else {
          const newVdom = component.render()
          console.log(prevVom, newVdom)
          patch(prevVom, newVdom)
          prevVom = newVdom
        }
      })


    }

    mountApp(App, document.getElementById('app'))


  </script>
</body>

</html>