Method shift

packages/core/src/lib/list-unit.ts:482–494

* Removes the first item from the list-value and returns it. \ * Dispatches a new copy of the value, without mutating the current-value. * * It only works if the Unit is not frozen, and the list is not empty isEmpty. * * @returns The shifted item. * * @triggers {

()

   * @category Customised Array.prototype
   */
  shift(): Item | undefined {
    if (this.isFrozen || this.isEmpty) {
      return;
    }
    const listShallowCopy = [...this.rawValue()];
    const shiftedItem = this.deepCopyMaybe(listShallowCopy.shift());
    this.updateValueAndCache(listShallowCopy);

    if (this.eventsSubject?.observers.length && !this.isMuted) {
      this.eventsSubject.next(new EventListUnitShift(shiftedItem));
    }
    return shiftedItem;
  }

  /**
   * Inserts new items at the start of the list-{@link value}. \