Function renderComponentSubTree

packages/server-renderer/src/render.ts:126–222

(
  instance: ComponentInternalInstance,
  slotScopeId?: string,
)

}

function renderComponentSubTree(
  instance: ComponentInternalInstance,
  slotScopeId?: string,
): SSRBuffer | Promise<SSRBuffer> {
  if (__DEV__) pushWarningContext(instance.vnode)
  const comp = instance.type as Component
  const { getBuffer, push } = createBuffer()
  if (isFunction(comp)) {
    let root = renderComponentRoot(instance)
    // #5817 scope ID attrs not falling through if functional component doesn't
    // have props
    if (!(comp as FunctionalComponent).props) {
      for (const key in instance.attrs) {
        if (key.startsWith(`data-v-`)) {
          ;(root.props || (root.props = {}))[key] = ``
        }
      }
    }
    renderVNode(push, (instance.subTree = root), instance, slotScopeId)
  } else {
    if (
      (!instance.render || instance.render === NOOP) &&
      !instance.ssrRender &&
      !comp.ssrRender &&
      isString(comp.template)
    ) {
      comp.ssrRender = ssrCompile(comp.template, instance)
    }

    const ssrRender = instance.ssrRender || comp.ssrRender
    if (ssrRender) {
      // optimized
      // resolve fallthrough attrs
      let attrs = instance.inheritAttrs !== false ? instance.attrs : undefined
      let hasCloned = false

      let cur = instance
      while (true) {
        const scopeId = cur.vnode.scopeId
        if (scopeId) {
          if (!hasCloned) {
            attrs = { ...attrs }
            hasCloned = true
          }
          attrs![scopeId] = ''
        }
        const parent = cur.parent
        if (parent && parent.subTree && parent.subTree === cur.vnode) {
          // parent is a non-SSR compiled component and is rendering this
          // component as root. inherit its scopeId if present.
          cur = parent
        } else {
          break
        }
      }

      if (slotScopeId) {
        if (!hasCloned) attrs = { ...attrs }