自己撸一个react_自撸

/**
 * 
 * @param {str|function} 类型，是字符串div 还是函数 
 * @param {*} jsx传递的属性 
 * @param  {...any} 子元素 
 */
function createElement(type, props, ...children) {
  delete props.__source
  return {
    type,
    props: {
      ...props,
      children: children.map(child =>
        typeof child === "object"
          ? child
          : createTextElement(child)
      ),
    },
  }
}
/** 文本类型vdom创建 */
function createTextElement(text) {
  return {
    type: "TEXT",
    props: {
      nodeValue: text,
      children: [],
    },
  }
}
/** 创建dom， 根据vdom or fiber */
function createDom(vdom){
  const dom = vdom.type == "TEXT"
    ? document.createTextNode("")
    : document.createElement(vdom.type)

  updateDom(dom, {}, vdom.props)
  // 设置属性

  return dom
  // // 递归渲染子元素
  // vdom.props.children.forEach(child => render(child, dom))
  // container.appendChild(dom)
}

// dom更新
function updateDom(dom, prevProps, nextProps) {
    Object.keys(prevProps)
    .filter(name=>name!=="children")
    .filter(name=> !(name in nextProps))
    .forEach(name => {
      // 删除
      if(name.slice(0,2)=='on'){
        dom.removeEventListener(name.slice(2).toLowerCase(), prevProps[name],false)
      }else{
        dom[name] = ''
      }
    })

    Object.keys(nextProps)
    .filter(name=>name!=="children")
    .forEach(name => {
      // 删除
      if(name.slice(0,2)=='on'){
        dom.addEventListener(name.slice(2).toLowerCase(), nextProps[name],false)
      }else{
        dom[name] = nextProps[name]
      }
    })

}


function commitRoot() {
  deletions.forEach(commitWork)
  commitWork(wipRoot.child)
  // 取消wip
  currentRoot = wipRoot
  wipRoot = null
}

function commitWork(fiber) {
  if (!fiber) {
    return
  }
  // const domParent = fiber.parent.dom


  let domParentFiber = fiber.parent
  while (!domParentFiber.dom) {
    domParentFiber = domParentFiber.parent
  }
  const domParent = domParentFiber.dom

  if (
    fiber.effectTag === "PLACEMENT" &&
    fiber.dom != null
  ) {
    domParent.appendChild(fiber.dom)
  } else if (
    fiber.effectTag === "UPDATE" &&
    fiber.dom != null
  ) {
    updateDom(
      fiber.dom,
      fiber.base.props,
      fiber.props
    )

  } else if (fiber.effectTag === "DELETION") {
    // domParent.removeChild(fiber.dom)
    commitDeletion(fiber, domParent)
  }
  // domParent.appendChild(fiber.dom)
  commitWork(fiber.child)
  commitWork(fiber.sibling)
}
function commitDeletion(fiber, domParent) {
  if (fiber.dom) {
    domParent.removeChild(fiber.dom)
  } else {
    commitDeletion(fiber.child, domParent)
  }
}

function render(vdom, container){
  // 设置全局 nextUnitOfWork 
  wipRoot = {
    dom: container,
    props: {
      children: [vdom],
    },
    base: currentRoot,
  }
  deletions = []
  nextUnitOfWork = wipRoot
}


let nextUnitOfWork = null
// 工作中的fiber
let wipRoot = null
let currentRoot = null
let deletions = null
// 任务调度
function workLoop(deadline) {
  // 有任务，并且当前帧还没结束
  // 没考虑到超时( deadline.didTimeout
  while (nextUnitOfWork && deadline.timeRemaining()>1) {
    // 获取下一个任务单元
    nextUnitOfWork = performUnitOfWork(
      nextUnitOfWork
    )
  }
  // 没有下个任务了 提交修改
  if (!nextUnitOfWork && wipRoot) {
    commitRoot()
  }
  requestIdleCallback(workLoop)
}
requestIdleCallback(workLoop)
function performUnitOfWork(fiber) {
  // TODO add dom node
  // TODO create new fibers
  // TODO return next unit of work

  // 如果没有dom 就不是入口，直接创建dom
  // if (!fiber.dom) {
  //   fiber.dom = createDom(fiber)
  // }
  // fiber父元素 这里先去掉直接操作dom的

  // 子元素遍历， 把children数组，变成链表
  // const elements = fiber.props.children
  // reconcileChildren(fiber, elements)

  
  // fiber遍历顺序
  // 子 =》 子的兄弟 => 没有兄弟了=> 父元素

  const isFunctionComponent = fiber.type instanceof Function
  if (isFunctionComponent) {
    updateFunctionComponent(fiber)
  } else {
    updateHostComponent(fiber)
  }
  if (fiber.child) {
    return fiber.child
  }
  let nextFiber = fiber
  while (nextFiber) {
    if (nextFiber.sibling) {
      return nextFiber.sibling
    }
    nextFiber = nextFiber.parent
  }
}

function useState(init){
  const oldHook =
  wipFiber.base &&
  wipFiber.base.hooks &&
  wipFiber.base.hooks[hookIndex]
  const hook = {
    state: oldHook ? oldHook.state : init,
    queue: [],
  }
  const actions = oldHook ? oldHook.queue : []
  actions.forEach(action => {
    hook.state = action
  })
  const setState = action => {
    hook.queue.push(action)
    wipRoot = {
      dom: currentRoot.dom,
      props: currentRoot.props,
      base: currentRoot,
    }
    nextUnitOfWork = wipRoot
    deletions = []
  }
  wipFiber.hooks.push(hook)
  hookIndex++
  return [hook.state, setState]
}
let wipFiber = null
let hookIndex = null

function updateFunctionComponent(fiber) {
  wipFiber = fiber
  hookIndex = 0
  wipFiber.hooks = []

  // 执行函数，传入props
  const children = [fiber.type(fiber.props)]
  reconcileChildren(fiber, children)
}
function updateHostComponent(fiber) {
  if (!fiber.dom) {
    fiber.dom = createDom(fiber)
  }
  reconcileChildren(fiber, fiber.props.children)
}
function reconcileChildren(wipFiber, elements) {
  let index = 0
  let oldFiber =
    wipFiber.base && wipFiber.base.child
  let prevSibling = null
  while (
    index < elements.length ||
    oldFiber != null
  ) {
    const element = elements[index]
    let newFiber = null
    // 对比
    const sameType =
      oldFiber &&
      element &&
      element.type == oldFiber.type
    if (sameType) {
      // update the node
      newFiber = {
        type: oldFiber.type,
        props: element.props,
        dom: oldFiber.dom,
        parent: wipFiber,
        base: oldFiber,
        effectTag: "UPDATE",
      }
    }
    if (element && !sameType) {
      // add this node
      newFiber = {
        type: element.type,
        props: element.props,
        dom: null,
        parent: wipFiber,
        base: null,
        effectTag: "PLACEMENT",
      }
    }
    if (oldFiber && !sameType) {
      // delete the oldFiber's node
      oldFiber.effectTag = "DELETION"
      deletions.push(oldFiber)
    }

    if (oldFiber) {
      oldFiber = oldFiber.sibling
    }
    if (index === 0) {
      wipFiber.child = newFiber
    } else if (element) {
      prevSibling.sibling = newFiber
    }
    prevSibling = newFiber
    index++
  }

  

}

class Component {
  constructor(props){
    this.props = props
    // this.state = {}
  }
}
function transfer(Component){
  return function(props){
    const component = new Component(props)
    // 简单的规避eslitn
    let initState = useState
    let [state, setState] = initState(component.state)
    component.props = props
    component.state = state
    component.setState = setState
    console.log(component)
    return component.render()
  }
}


export default {
  createElement,
  render,
  useState,
  Component,
  transfer
}
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