Method getScrollPosition

src/react-list.js:182–204

()

  }

  getScrollPosition() {
    // Cache scroll position as this causes a forced synchronous layout.
    if (typeof this.cachedScrollPosition === 'number') {
      return this.cachedScrollPosition;
    }
    const { scrollParent } = this;
    const { axis } = this.props;
    const scrollKey = SCROLL_START_KEYS[axis];
    const actual =
      scrollParent === window
        ? // Firefox always returns document.body[scrollKey] as 0 and Chrome/Safari
          // always return document.documentElement[scrollKey] as 0, so take
          // whichever has a value.
          document.body[scrollKey] || document.documentElement[scrollKey]
        : scrollParent[scrollKey];
    const max =
      this.getScrollSize() - this.props.scrollParentViewportSizeGetter(this);
    const scroll = Math.max(0, Math.min(actual, max));
    const el = this.getEl();
    this.cachedScrollPosition =
      this.getOffset(scrollParent) + scroll - this.getOffset(el);
    return this.cachedScrollPosition;
  }

  setScroll(offset) {
    const { scrollParent } = this;