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

import {
  isArray,
  normalizeClass,
  normalizeStyle,
  toDisplayString,
} from '@vue/shared'
import type { Block, ParentBlock } from './render'

export function insert(block: Block, parent: Node, 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)
    parent.insertBefore(block.anchor, anchor)
  }
  // }
}

export function prepend(parent: ParentBlock, ...nodes: Node[]) {
  if (parent instanceof Node) {
    // TODO use insertBefore for better performance https://jsbench.me/rolpg250hh/1
    parent.prepend(...nodes)
  } else if (isArray(parent)) {
    parent.unshift(...nodes)
  }
}

export function append(parent: ParentBlock, ...nodes: Node[]) {
  if (parent instanceof Node) {
    // TODO use insertBefore for better performance
    parent.append(...nodes)
  } else if (isArray(parent)) {
    parent.push(...nodes)
  }
}

export function remove(block: Block, parent: ParentNode) {
  if (block instanceof DocumentFragment) {
    remove(Array.from(block.childNodes), parent)
  } else 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: Node, oldVal: any, newVal: any) {
  if ((newVal = toDisplayString(newVal)) !== oldVal) {
    el.textContent = newVal
  }
}

export function setHtml(el: Element, oldVal: any, newVal: any) {
  if (newVal !== oldVal) {
    el.innerHTML = 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 setDOMProp(el: any, key: string, oldVal: any, newVal: any) {
  // TODO special checks
  if (newVal !== oldVal) {
    el[key] = newVal
  }
}

export function setDynamicProp(
  el: Element,
  key: string,
  oldVal: any,
  newVal: any,
) {
  if (key === 'class') {
    setClass(el, oldVal, newVal)
  } else if (key === 'style') {
    setStyle(el as HTMLElement, oldVal, newVal)
  } else if (
    key[0] === '.'
      ? ((key = key.slice(1)), true)
      : key[0] === '^'
        ? ((key = key.slice(1)), false)
        : key in el
  ) {
    setDOMProp(el, key, oldVal, newVal)
  } else {
    // TODO special checks
    setAttr(el, key, oldVal, newVal)
  }
}

type Children = Record<number, [ChildNode, Children]>
export function children(n: Node): Children {
  const result: Children = {}
  const array = Array.from(n.childNodes)
  for (let i = 0; i < array.length; i++) {
    const n = array[i]
    result[i] = [n, children(n)]
  }
  return result
}

export function createTextNode(val: unknown): Text {
  // eslint-disable-next-line no-restricted-globals
  return document.createTextNode(toDisplayString(val))
}