vue3-core/packages/scheduler/src/sync.ts

70 lines
1.6 KiB
TypeScript

const queue: Array<() => void> = []
const postFlushCbs: Array<() => void> = []
const p = Promise.resolve()
let isFlushing = false
export function nextTick(fn?: () => void): Promise<void> {
return p.then(fn)
}
export function queueJob(
job: () => void,
postFlushCb?: () => void,
onError?: (err: Error) => void
) {
if (queue.indexOf(job) === -1) {
queue.push(job)
if (!isFlushing) {
isFlushing = true
const p = nextTick(flushJobs)
if (onError) p.catch(onError)
}
}
if (postFlushCb && postFlushCbs.indexOf(postFlushCb) === -1) {
postFlushCbs.push(postFlushCb)
}
}
const RECURSION_LIMIT = 100
type JobCountMap = Map<Function, number>
function flushJobs(seenJobs?: JobCountMap) {
let job
if (__DEV__) {
seenJobs = seenJobs || new Map()
}
while ((job = queue.shift())) {
if (__DEV__) {
const seen = seenJobs as JobCountMap
if (!seen.has(job)) {
seen.set(job, 1)
} else {
const count = seen.get(job) as number
if (count > RECURSION_LIMIT) {
throw new Error(
'Maximum recursive updates exceeded. ' +
"You may have code that is mutating state in your component's " +
'render function or updated hook.'
)
} else {
seen.set(job, count + 1)
}
}
}
job()
}
const cbs = postFlushCbs.slice()
postFlushCbs.length = 0
for (let i = 0; i < cbs.length; i++) {
cbs[i]()
}
// some postFlushCb queued jobs!
// keep flushing until it drains.
if (queue.length) {
flushJobs(seenJobs)
} else {
isFlushing = false
}
}