example.html

<my-component></my-component>

<script type="module">
  import {
    defineComponent,
    reactive,
    html,
    onMounted,
    onUpdated,
    onUnmounted
  } from './index.js'

  defineComponent('my-component', () => {
    const state = reactive({
      text: 'hello',
      show: true
    })
    const toggle = () => {
      state.show = !state.show
    }
    const onInput = e => {
      state.text = e.target.value
    }

    return () => html`
      <button @click=${toggle}>toggle child</button>
      <p>
      ${state.text} <input value=${state.text} @input=${onInput}>
      </p>
      ${state.show ? html`<my-child msg=${state.text}></my-child>` : ``}
    `
  })

  defineComponent('my-child', ['msg'], (props) => {
    const state = reactive({ count: 0 })
    const increase = () => {
      state.count++
    }

    onMounted(() => {
      console.log('child mounted')
    })

    onUpdated(() => {
      console.log('child updated')
    })

    onUnmounted(() => {
      console.log('child unmounted')
    })

    return () => html`
      <p>${props.msg}</p>
      <p>${state.count}</p>
      <button @click=${increase}>increase</button>
    `
  })
</script>