Function trigger

packages/reactivity/src/dep.ts:294–389

(
  target: object,
  type: TriggerOpTypes,
  key?: unknown,
  newValue?: unknown,
  oldValue?: unknown,
  oldTarget?: Map<unknown, unknown> | Set<unknown>,
)

 * @param key - Can be used to target a specific reactive property in the target object.
 */
export function trigger(
  target: object,
  type: TriggerOpTypes,
  key?: unknown,
  newValue?: unknown,
  oldValue?: unknown,
  oldTarget?: Map<unknown, unknown> | Set<unknown>,
): void {
  const depsMap = targetMap.get(target)
  if (!depsMap) {
    // never been tracked
    globalVersion++
    return
  }

  const run = (dep: Dep | undefined) => {
    if (dep) {
      if (__DEV__) {
        dep.trigger({
          target,
          type,
          key,
          newValue,
          oldValue,
          oldTarget,
        })
      } else {
        dep.trigger()
      }
    }
  }

  startBatch()

  if (type === TriggerOpTypes.CLEAR) {
    // collection being cleared
    // trigger all effects for target
    depsMap.forEach(run)
  } else {
    const targetIsArray = isArray(target)
    const isArrayIndex = targetIsArray && isIntegerKey(key)

    if (targetIsArray && key === 'length') {
      const newLength = Number(newValue)
      depsMap.forEach((dep, key) => {
        if (
          key === 'length' ||
          key === ARRAY_ITERATE_KEY ||
          (!isSymbol(key) && key >= newLength)
        ) {
          run(dep)
        }
      })
    } else {
      // schedule runs for SET | ADD | DELETE
      if (key !== void 0 || depsMap.has(void 0)) {
        run(depsMap.get(key))
      }