commitWork
1 )概述
- 在 react commit 阶段的 commitRoot 第二个while循环中
- 调用了 commitAllHostEffects,这个函数不仅仅处理了新增节点
- 若一个节点已经存在,当它有新的内容要更新或者是它的attributes要更新
- 这个时候,就需要调用
commitWork
2 )源码
定位到 packages/react-reconciler/src/ReactFiberCommitWork.js#L1033
js
function commitWork(current: Fiber | null, finishedWork: Fiber): void {
if (!supportsMutation) {
switch (finishedWork.tag) {
case FunctionComponent:
case ForwardRef:
case MemoComponent:
case SimpleMemoComponent: {
commitHookEffectList(UnmountMutation, MountMutation, finishedWork);
return;
}
}
commitContainer(finishedWork);
return;
}
// 首先,根据不同的tag类型来执行不同的操作
switch (finishedWork.tag) {
case FunctionComponent:
case ForwardRef:
case MemoComponent:
case SimpleMemoComponent: {
commitHookEffectList(UnmountMutation, MountMutation, finishedWork);
return;
}
// ClassComponent 不在这里的执行范围内,所以它就return了
case ClassComponent: {
return;
}
case HostComponent: {
const instance: Instance = finishedWork.stateNode;
// // 如果instance不等于null,就代表 instance 对应的节点已经创建了
if (instance != null) {
// Commit the work prepared earlier.
const newProps = finishedWork.memoizedProps;
// For hydration we reuse the update path but we treat the oldProps
// as the newProps. The updatePayload will contain the real change in
// this case.
const oldProps = current !== null ? current.memoizedProps : newProps;
const type = finishedWork.type;
// TODO: Type the updateQueue to be specific to host components.
// 获取了一个 updatePayload 等于 finishedWork.updateQueue
// 在 completeWork 的时候,对于 HostComponent 进行了新老 props 的一个对比
// 这个对比的结果就是返回一个叫做 updatePayload 这么一个数组
// 这个数组是以2为单位,就是说一个key一个value, 它的第一位是key,第二位是value,然后这样的形式一个一个往后面堆叠
// 拿到这么一个 updatePayload 之后,我们就知道在commit阶段要去执行怎么样的一个更新操作
const updatePayload: null | UpdatePayload = (finishedWork.updateQueue: any);
finishedWork.updateQueue = null;
// 存在 updatePayload 则执行 commitUpdate
if (updatePayload !== null) {
commitUpdate(
instance,
updatePayload,
type,
oldProps,
newProps,
finishedWork,
);
}
}
return;
}
case HostText: {
invariant(
finishedWork.stateNode !== null,
'This should have a text node initialized. This error is likely ' +
'caused by a bug in React. Please file an issue.',
);
const textInstance: TextInstance = finishedWork.stateNode;
const newText: string = finishedWork.memoizedProps;
// For hydration we reuse the update path but we treat the oldProps
// as the newProps. The updatePayload will contain the real change in
// this case.
const oldText: string =
current !== null ? current.memoizedProps : newText;
commitTextUpdate(textInstance, oldText, newText);
return;
}
case HostRoot: {
return;
}
case Profiler: {
return;
}
case SuspenseComponent: {
let newState: SuspenseState | null = finishedWork.memoizedState;
let newDidTimeout;
let primaryChildParent = finishedWork;
if (newState === null) {
newDidTimeout = false;
} else {
newDidTimeout = true;
primaryChildParent = finishedWork.child;
if (newState.timedOutAt === NoWork) {
// If the children had not already timed out, record the time.
// This is used to compute the elapsed time during subsequent
// attempts to render the children.
newState.timedOutAt = requestCurrentTime();
}
}
if (primaryChildParent !== null) {
hideOrUnhideAllChildren(primaryChildParent, newDidTimeout);
}
return;
}
case IncompleteClassComponent: {
return;
}
default: {
invariant(
false,
'This unit of work tag should not have side-effects. This error is ' +
'likely caused by a bug in React. Please file an issue.',
);
}
}
}
-
进入
commitUpdate
js// packages/react-dom/src/client/ReactDOMHostConfig.js#L324 export function commitUpdate( domElement: Instance, updatePayload: Array<mixed>, type: string, oldProps: Props, newProps: Props, internalInstanceHandle: Object, ): void { // Update the props handle so that we know which props are the ones with // with current event handlers. updateFiberProps(domElement, newProps); // 将新的props挂载到新的属性上 // Apply the diff to the DOM node. updateProperties(domElement, updatePayload, type, oldProps, newProps); } // packages/react-dom/src/client/ReactDOMComponentTree.js#L85 export function updateFiberProps(node, props) { node[internalEventHandlersKey] = props; } // packages/react-dom/src/client/ReactDOMComponent.js#L775 // Apply the diff. export function updateProperties( domElement: Element, updatePayload: Array<any>, tag: string, lastRawProps: Object, nextRawProps: Object, ): void { // Update checked *before* name. // In the middle of an update, it is possible to have multiple checked. // When a checked radio tries to change name, browser makes another radio's checked false. // 像是 radio 可以设置 value 绑定来设置 // 对于radio标签,设置通过 value 的绑定来进行是否选中的控制, 相当于是要把value转化成哪一个radio标签,它的checked属性是等于true的这么一种情况 // 这是为什么当初在执行 diff property 的时候,判断如果这个标签是input,它的 updatePayload 直接等于了一个空数组 // 也就是说,即便我们后续 updatePayload 的里面没有放任何的内容,但它返回的仍然是一个空数组,仍然要执行到我们这个 updateProperties 方法里面 // 因为最终我们要去根据一些不同的情况来更新,像radio标签,checkbox 标签 的一个 checked 相关的一些状态 if ( tag === 'input' && nextRawProps.type === 'radio' && nextRawProps.name != null ) { ReactDOMInput.updateChecked(domElement, nextRawProps); } const wasCustomComponentTag = isCustomComponent(tag, lastRawProps); const isCustomComponentTag = isCustomComponent(tag, nextRawProps); // Apply the diff. // 更新 dom 节点的 properties updateDOMProperties( domElement, updatePayload, wasCustomComponentTag, isCustomComponentTag, ); // TODO: Ensure that an update gets scheduled if any of the special props // changed. // 表单标签的处理 // 其实就是把这些 input, textarea, select 标签, 特殊的一些属性,一些 attribute 给它进行一个更新的一个过程 switch (tag) { case 'input': // Update the wrapper around inputs *after* updating props. This has to // happen after `updateDOMProperties`. Otherwise HTML5 input validations // raise warnings and prevent the new value from being assigned. ReactDOMInput.updateWrapper(domElement, nextRawProps); break; case 'textarea': ReactDOMTextarea.updateWrapper(domElement, nextRawProps); break; case 'select': // <select> value update needs to occur after <option> children // reconciliation ReactDOMSelect.postUpdateWrapper(domElement, nextRawProps); break; } } // packages/react-dom/src/client/ReactDOMInput.js#L128 export function updateChecked(element: Element, props: Object) { const node = ((element: any): InputWithWrapperState); const checked = props.checked; if (checked != null) { // dom操作 DOMPropertyOperations.setValueForProperty(node, 'checked', checked, false); } } // packages/react-dom/src/shared/isCustomComponent.js#L10 function isCustomComponent(tagName: string, props: Object) { // 它根据标签名字上,是否有 - 的存在, 并且 props.is 是 string 则是 if (tagName.indexOf('-') === -1) { return typeof props.is === 'string'; } // 有 - 的,屏蔽自有的一些,排除之后其他都算 自定义 switch (tagName) { // These are reserved SVG and MathML elements. // We don't mind this whitelist too much because we expect it to never grow. // The alternative is to track the namespace in a few places which is convoluted. // https://w3c.github.io/webcomponents/spec/custom/#custom-elements-core-concepts case 'annotation-xml': case 'color-profile': case 'font-face': case 'font-face-src': case 'font-face-uri': case 'font-face-format': case 'font-face-name': case 'missing-glyph': return false; default: return true; } } // packages/react-dom/src/client/ReactDOMComponent.js#L326 function updateDOMProperties( domElement: Element, updatePayload: Array<any>, wasCustomComponentTag: boolean, isCustomComponentTag: boolean, ): void { // TODO: Handle wasCustomComponentTag // 遍历这个updatepaylow的这个数组,然后记住这边的下标增加是每次加2,而不是加1了 for (let i = 0; i < updatePayload.length; i += 2) { // i 对应的就是 propKey, 然后i加1对应的就是 propValue const propKey = updatePayload[i]; const propValue = updatePayload[i + 1]; // 如果是style,会对每一个style的属性来执行 if (propKey === STYLE) { // 里面会遍历这个style对象里面的每一个style属性,然后去设置对应的值 // 我们拿到一个对象,最终如何给它转换成真正的CSS属性给它设置上去的一个过程 // 其中还要考虑一些属性是删除的操作 CSSPropertyOperations.setValueForStyles(domElement, propValue); } else if (propKey === DANGEROUSLY_SET_INNER_HTML) { setInnerHTML(domElement, propValue); } else if (propKey === CHILDREN) { setTextContent(domElement, propValue); } else { // 对于其他属性的处理 DOMPropertyOperations.setValueForProperty( domElement, propKey, propValue, isCustomComponentTag, ); } } } // packages/react-dom/src/client/ReactDOMHostConfig.js#L343 export function commitTextUpdate( textInstance: TextInstance, oldText: string, newText: string, ): void { textInstance.nodeValue = newText; }
-
对于 HostComponent 来说
- 因为更新的过程,有一大部分是放在
completeUnitOfWork
里面去做了 - 在
completeWork
的时候会获得这个updatePayload
- 这个 payload 已经告诉我们具体要做哪些属性的操作了
- 它里面也包含了我们有一些 attribute 要删除的情况
- 就是说它的 value 为 null 的情况, 标示着这个属性是要被删除的
- 所以, 那一部分工作做完了之后,到这里其实已经比较的简单了
- 只需要根据
updatePayload
里面相关的内容进行一个整体的更新就可以了
- 因为更新的过程,有一大部分是放在
-
对于 HostText 它也要进行一个更新,它调用了一个
commitTextUpdate
-
以上就是整个 commitWork 里面做的事情, 具体的细节写在代码注释里