vue3-core/packages/runtime-vapor/src/render.ts

import {
  effectScope,
  normalizeClass,
  normalizeStyle,
  toDisplayString
} from 'vue'
import { isArray } from '@vue/shared'

export type Block = Node | Fragment | Block[]
export type Fragment = { nodes: Block; anchor?: Node }
export type BlockFn = (props?: any) => Block

export function render(
  comp: BlockFn,
  container: string | ParentNode
): () => void {
  const scope = effectScope()
  const block = scope.run(() => comp())!
  insert(block, (container = normalizeContainer(container)))
  return () => {
    scope.stop()
    remove(block, container as ParentNode)
  }
}

export function normalizeContainer(container: string | ParentNode): ParentNode {
  return typeof container === 'string'
    ? (document.querySelector(container) as ParentNode)
    : container
}

export function insert(
  block: Block,
  parent: ParentNode,
  anchor: Node | null = null
) {
  // if (!isHydrating) {
  if (block instanceof Node) {
    parent.insertBefore(block, anchor)
  } else if (isArray(block)) {
    for (const child of block) insert(child, parent, anchor)
  } else {
    insert(block.nodes, parent, anchor)
    block.anchor && parent.insertBefore(block.anchor, anchor)
  }
  // }
}

export function remove(block: Block, parent: ParentNode) {
  if (block instanceof Node) {
    parent.removeChild(block)
  } else if (isArray(block)) {
    for (const child of block) remove(child, parent)
  } else {
    remove(block.nodes, parent)
    block.anchor && parent.removeChild(block.anchor)
  }
}

export function setText(el: Element, oldVal: any, newVal: any) {
  if ((newVal = toDisplayString(newVal)) !== oldVal) {
    el.textContent = newVal
  }
}

export function setClass(el: Element, oldVal: any, newVal: any) {
  if ((newVal = normalizeClass(newVal)) !== oldVal && (newVal || oldVal)) {
    el.className = newVal
  }
}

export function setStyle(el: HTMLElement, oldVal: any, newVal: any) {
  if ((newVal = normalizeStyle(newVal)) !== oldVal && (newVal || oldVal)) {
    if (typeof newVal === 'string') {
      el.style.cssText = newVal
    } else {
      // TODO
    }
  }
}

export function setAttr(el: Element, key: string, oldVal: any, newVal: any) {
  if (newVal !== oldVal) {
    if (newVal != null) {
      el.setAttribute(key, newVal)
    } else {
      el.removeAttribute(key)
    }
  }
}

export function setDynamicProp(el: Element, key: string, val: any) {
  if (key === 'class') {
    setClass(el, void 0, val)
  } else if (key === 'style') {
    setStyle(el as HTMLElement, void 0, val)
  } else if (key in el) {
    ;(el as any)[key] = val
  } else {
    // TODO special checks
    setAttr(el, key, void 0, val)
  }
}