next-tick.ts

import { Current } from './current'
import { TaroRootElement } from './dom/root'
import env from './env'

import type { TFunc } from './interface'

const TIMEOUT = 100

export const nextTick = (cb: TFunc, ctx?: Record<string, any>) => {
  const beginTime = Date.now()
  const router = Current.router

  const timerFunc = () => {
    setTimeout(function () {
      ctx ? cb.call(ctx) : cb()
    }, 1)
  }

  if (router === null) return timerFunc()

  const path = router.$taroPath

  /**
   * 三种情况
   *   1. 调用 nextTick 时，pendingUpdate 已经从 true 变为 false（即已更新完成），那么需要光等 100ms
   *   2. 调用 nextTick 时，pendingUpdate 为 true，那么刚好可以搭上便车
   *   3. 调用 nextTick 时，pendingUpdate 还是 false，框架仍未启动更新逻辑，这时最多轮询 100ms，等待 pendingUpdate 变为 true。
   */
  function next () {
    const pageElement: TaroRootElement | null = env.document.getElementById<TaroRootElement>(path)
    if (pageElement?.pendingUpdate) {
      if (process.env.TARO_PLATFORM === 'web') {
        // eslint-disable-next-line dot-notation
        pageElement.firstChild?.['componentOnReady']?.().then(() => {
          timerFunc()
        }) ?? timerFunc()
      } else {
        pageElement.enqueueUpdateCallback(cb, ctx)
      }
    } else if (Date.now() - beginTime > TIMEOUT) {
      timerFunc()
    } else {
      setTimeout(() => next(), 20)
    }
  }

  next()
}