petite-vue源码剖析-ref的工作原理

//文件 ./src/directives/ref.ts

export const ref: Directive = ({
  el,
  ctx: {
    scope: { $refs }
  },
  get,
  effect
}) => {
  let prevRef: any
  effect(() => {
    // 获取指向元素的属性名称
    const ref = get()
    $refs[ref] = el
    // 由于属性名称是可以动态生成的(:ref="name")，若新旧对应的属性名称不同，则清理旧属性
    if (prevRef && ref != prevRef) {
      delete $refs[prevRef]
    }
    prevRef = ref
  })

  return () => {
    prevRef && delete $refs[prevRef]
  }
}

//文件 ./src/context.ts

export const createScopedContext = (ctx: Context, data = {}) => {
  onst parentScope = ctx.scope
  const mergedScope = Object.create(parentScope)
  Object.defineProperties(mergedScope, Object.getOwnPropertyDescriptors(data))
  // $refs构成$refs对象的原型链
  mergedScope.$refs = Object.create(parentScope.$refs)
  // ......
}

createApp({
  App: {
    $template: `
    <div ref="container">
      <div v-scope="Modal"></div>
    </div>
    `,
    Modal: {
      $template: `
      <button @click="handleHide">Hide</button>
      `,
      handleHide() {
        this.$refs.container.style.display = 'none'
      }
    }
  }
}).mount('[v-scope]')