vue3源码阅读【runtime-core\src\renderer.ts】【processComponent】

processComponent

• 执行 processComponent 时， 如果 n1 为空，说明了mount 过程调用， 执行 mountComponent ； 否则就是 updateComponent

const processComponent = (
    n1: VNode | null,
    n2: VNode,
    container: RendererElement,
    anchor: RendererNode | null,
    parentComponent: ComponentInternalInstance | null,
    parentSuspense: SuspenseBoundary | null,
    isSVG: boolean,
    slotScopeIds: string[] | null,
    optimized: boolean
  ) => {
    n2.slotScopeIds = slotScopeIds
    if (n1 == null) {
      if (n2.shapeFlag & ShapeFlags.COMPONENT_KEPT_ALIVE) {
        ;(parentComponent!.ctx as KeepAliveContext).activate(
          n2,
          container,
          anchor,
          isSVG,
          optimized
        )
      } else {
        mountComponent(
          n2,
          container,
          anchor,
          parentComponent,
          parentSuspense,
          isSVG,
          optimized
        )
      }
    } else {
      updateComponent(n1, n2, optimized)
    }
  }