updateHostComponent
hostComponent
即指原生的HTML标签。
context
相关的看这里
tryToClaimNextHydratableInstance
是进行hydrate
的操作,也就是复用原本存在的root
的内部的DOM节点,详细可以看这里
export function shouldDeprioritizeSubtree(type: string, props: Props): boolean {
return !!props.hidden;
}
shouldDeprioritizeSubtree
判断了是否有hidden
这个prop
,如果这个节点是AsyncMode
的并且有hidden
,就设置expirationTime
为Never
。
设置为Never
是什么意思?意味着他的优先级是最低的,知道没有任何其他任务的时候这个才会被执行,详见这里
然后就是常规的处理children
的逻辑,就不详细讲了
function updateHostComponent(current, workInProgress, renderExpirationTime) {
pushHostContext(workInProgress);
if (current === null) {
tryToClaimNextHydratableInstance(workInProgress);
}
const type = workInProgress.type;
const nextProps = workInProgress.pendingProps;
const prevProps = current !== null ? current.memoizedProps : null;
let nextChildren = nextProps.children;
const isDirectTextChild = shouldSetTextContent(type, nextProps);
if (isDirectTextChild) {
// We special case a direct text child of a host node. This is a common
// case. We won't handle it as a reified child. We will instead handle
// this in the host environment that also have access to this prop. That
// avoids allocating another HostText fiber and traversing it.
nextChildren = null;
} else if (prevProps !== null && shouldSetTextContent(type, prevProps)) {
// If we're switching from a direct text child to a normal child, or to
// empty, we need to schedule the text content to be reset.
workInProgress.effectTag |= ContentReset;
}
markRef(current, workInProgress);
// Check the host config to see if the children are offscreen/hidden.
if (
renderExpirationTime !== Never &&
workInProgress.mode & AsyncMode &&
shouldDeprioritizeSubtree(type, nextProps)
) {
// Schedule this fiber to re-render at offscreen priority. Then bailout.
workInProgress.expirationTime = Never;
workInProgress.memoizedProps = nextProps;
return null;
}
reconcileChildren(
current,
workInProgress,
nextChildren,
renderExpirationTime,
);
memoizeProps(workInProgress, nextProps);
return workInProgress.child;
}
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