Function scrollToIndex

VirtualizedList.js:203–223

(params: {
    animated?: ?boolean, index: number, viewOffset?: number, viewPosition?: number
  })

  // scrollToIndex may be janky without getItemLayout prop
  scrollToIndex(params: {
    animated?: ?boolean, index: number, viewOffset?: number, viewPosition?: number
  }) {
    const {data, horizontal, getItemCount, getItemLayout} = this.props;
    const {animated, index, viewOffset, viewPosition} = params;
    invariant(
      index >= 0 && index < getItemCount(data),
      `scrollToIndex out of range: ${index} vs ${getItemCount(data) - 1}`,
    );
    invariant(
      getItemLayout || index < this._highestMeasuredFrameIndex,
      'scrollToIndex should be used in conjunction with getItemLayout, ' +
        'otherwise there is no way to know the location of an arbitrary index.',
    );
    const frame = this._getFrameMetricsApprox(index);
    const offset = Math.max(
      0,
      frame.offset - (viewPosition || 0) * (this._scrollMetrics.visibleLength - frame.length),
    ) - (viewOffset || 0);
    this._scrollRef.scrollTo(horizontal ? {x: offset, animated} : {y: offset, animated});
  }

  // scrollToItem may be janky without getItemLayout prop. Required linear scan through items -
  // use scrollToIndex instead if possible.