我有一个山视差场景，在一个容器中有四个图像，当容器在屏幕底部的视口中可见时，视差滚动。动画工作，但当容器开始离开屏幕顶部的视口时，视差开始反转。您可以在这里看到工作示例：https://jsfiddle.net/breonwilliams/n2tspLzk/12/
视差的脚本如下。当容器div离开视区时，我怎样才能停止视差滚动？

/**
   * Creates an IntersectionObserver and starts observing all elements found using the selector.
   *
   * @param {String} selector: Selector used to find all target elements
   * @param {Number[]} threshold: Array of intersection ratios, at which the callback is executed
   * @param {Function} callback: Callback executed for each threshold
   */
  function observe(selector, threshold, callback) {
    const elements = document.querySelectorAll(selector);
    const options = {
      rootMargin: '-100px',
      threshold: threshold,
    };

    const observer = new IntersectionObserver(callback, options);

    for (const element of elements) {
      observer.observe(element);
    }
  }

  /**
   * Creates a CSS translateY value.
   *
   * @param {Number} ratio: A number between 0 and 1
   * @param {String} total: A valid CSS number and unit (10px, 100%, 30vh, …)
   * @return {String} The CSS translateY value.
   */
  function translateY(ratio, total) {
    return `translateY(calc(-${ratio} * ${total})`;
  }

  /**
   * Callback executed for the box elements
   *
   * @see https://developer.mozilla.org/en-US/docs/Web/API/Intersection_Observer_API
   *
   * @param {IntersectionObserverEntry[]} entries: Intersection Observer Entries
   * @param {IntersectionObserver} observer: Intersection Observer
   */
  function boxParallax(entries, observer) {
    for (const entry of entries) {
      if (entry.isIntersecting) {
        entry.target.style.transform = translateY(entry.intersectionRatio, '-140px');
      }
    }
  }

  function boxParallax_two(entries, observer) {
    for (const entry of entries) {
      if (entry.isIntersecting) {
        entry.target.style.transform = translateY(entry.intersectionRatio, '-270px');
      }
    }
  }

  function boxParallax_three(entries, observer) {
    for (const entry of entries) {
      if (entry.isIntersecting) {
        entry.target.style.transform = translateY(entry.intersectionRatio, '-300px');
      }
    }
  }

  function boxParallax_four(entries, observer) {
    for (const entry of entries) {
      if (entry.isIntersecting) {
        entry.target.style.transform = translateY(entry.intersectionRatio, '-350px');
      }
    }
  }
  /**
   * Create one threshold for each intersection ratio.
   *
   * @return {Number[]}
   */
  function createThreshold() {
    const threshold = [];
    for (let i = 0; i <= 1.0; i += 0.01) {
      threshold.push(i);
    }

    return threshold;
  }

  const threshold = createThreshold();
  observe('.two', threshold, boxParallax);
  observe('.three', threshold, boxParallax_two);
  observe('.four', threshold, boxParallax_three);
  observe('.five', threshold, boxParallax_four);

});