简化版 Ref 实现 #

export function createVnode(type, props, children?) {
  const shapeFlag = isString(type)
    ? ShapeFlags.ELEMENT // 元素
    : isObject(type)
    ? ShapeFlags.STATEFUL_COMPONENT // 组件
    : isFunction(type)
    ? ShapeFlags.FUNCTIONAL_COMPONENT
    : 0;
  const vnode = {
    __v_isVnode: true,
    type,
    props,
    children,
    key: props?.key,
    el: null,
    shapeFlag,
    ref: props && props.ref, // 提取ref
  };

function setRef(rawRef, vnode) {
  const refValue =
    vnode.shapeFlag & ShapeFlags.STATEFUL_COMPONENT
      ? vnode.component.exposed || vnode.component!.proxy
      : vnode.el;

  if (rawRef) {
    rawRef.value = refValue;
  }
}
const patch = (n1, n2, container, anchor = null, parentComponent = null) => {
  // ...
  if (ref !== null) {
    // 新ref 和 老ref
    setRef(ref, n2);
  }
};