常见的电商平台有哪些,东莞市网络优化推广平台,wordpress 评论倒序,嵌入式软件开发项目PortalComponent 1 #xff09;概述
React Portal之所以叫Portal#xff0c;因为做的就是和“传送门”一样的事情render到一个组件里面去#xff0c;实际改变的是网页上另一处的DOM结构主要关注 portal的创建, 调和, 更新过程
2 #xff09;源码
定位到 packages/react-…PortalComponent 1 概述
React Portal之所以叫Portal因为做的就是和“传送门”一样的事情render到一个组件里面去实际改变的是网页上另一处的DOM结构主要关注 portal的创建, 调和, 更新过程
2 源码
定位到 packages/react-dom/src/client/ReactDOM.js#L576
function createPortal(children: ReactNodeList,container: DOMContainer,key: ?string null,
) {invariant(isValidContainer(container),Target container is not a DOM element.,);// TODO: pass ReactDOM portal implementation as third argumentreturn ReactPortal.createPortal(children, container, null, key);
} 这里调用的是 ReactPortal.createPortal, 进入 // packages/shared/ReactPortal.js#L14
export function createPortal(children: ReactNodeList,containerInfo: any,// TODO: figure out the API for cross-renderer implementation.implementation: any,key: ?string null,
): ReactPortal {return {// This tag allow us to uniquely identify this as a React Portal$$typeof: REACT_PORTAL_TYPE,key: key null ? null : key,children,containerInfo, // dom 挂载节点implementation,};
}这里返回一个对象类似于 ReactElement区别在于 $$typeof 和 containerInfo 需要的挂载点 对于 REACT_PORTAL_TYPE 类型的组件在 reconcile 时, 看下具体操作, 找到 reconcileSinglePortal // packages/react-reconciler/src/ReactChildFiber.js#L1171
function reconcileSinglePortal(returnFiber: Fiber,currentFirstChild: Fiber | null,portal: ReactPortal,expirationTime: ExpirationTime,
): Fiber {const key portal.key; // 当前的 keylet child currentFirstChild;// 如果 存在 child, 对比 child.key keywhile (child ! null) {// TODO: If key null and child.key null, then this only applies to// the first item in the list.if (child.key key) {// 关注这里有 containerInfo 的对比portal 需要关心渲染到的节点是否有变化// 如果节点有变化那么这个 portal 的渲染过程也会有变化// 都符合说明老节点都可以复用if (child.tag HostPortal child.stateNode.containerInfo portal.containerInfo child.stateNode.implementation portal.implementation) {deleteRemainingChildren(returnFiber, child.sibling); // 删除其他节点// 通过 useFiber 复用这个节点const existing useFiber(child,portal.children || [],expirationTime,);existing.return returnFiber;return existing;} else {// key相同但是不符合上述if, 没法复用删除干净deleteRemainingChildren(returnFiber, child);break;}} else {// key 不同删除当前节点deleteChild(returnFiber, child);}child child.sibling;}// 创建一个 portal 的 fiber 对象const created createFiberFromPortal(portal,returnFiber.mode,expirationTime,);created.return returnFiber;return created;
}对于更新一个portal节点进入 updatePortalComponent // packages/react-reconciler/src/ReactFiberBeginWork.js#L1322
function updatePortalComponent(current: Fiber | null,workInProgress: Fiber,renderExpirationTime: ExpirationTime,
) {// 挂载点处理pushHostContainer(workInProgress, workInProgress.stateNode.containerInfo);const nextChildren workInProgress.pendingProps; // 这里 pendingProps 是 childrenif (current null) {// Portals are special because we dont append the children during mount// but at commit. Therefore we need to track insertions which the normal// flow doesnt do during mount. This doesnt happen at the root because// the root always starts with a current with a null child.// TODO: Consider unifying this with how the root works.workInProgress.child reconcileChildFibers(workInProgress,null,nextChildren,renderExpirationTime,);} else {reconcileChildren(current,workInProgress,nextChildren,renderExpirationTime,);}return workInProgress.child;
}之前梳理过的 API 不再赘述一些API的调用在源码的注释中
