Options.js

import React, { Component } from 'react';
import cx from 'classnames';
import Option from './Option';
import { getOptionIndex, isOptGroup } from './utils';

export default class Options extends Component {
  componentWillReceiveProps({ options, highlightedOption }) {
    this.scrollTo({ options, highlightedOption });
  }

  componentDidMount() {
    let { options, highlightedOption } = this.props;
    this.optionsListOffsetHeight = this.optionsList.offsetHeight;
    this.scrollTo({ options, highlightedOption });
  }

  componentDidUpdate() {
    if (!this.optionsListOffsetHeight) {
      this.optionsListOffsetHeight = this.optionsList.offsetHeight;
    }
  }

  scrollTo({ options, highlightedOption }) {
    if (highlightedOption) {
      let optionIndex = getOptionIndex(options, highlightedOption);
      let $option = this.optionsList.querySelector(`[data-option-index="${optionIndex}"]`);
      let delta = 0;
      if ($option) {
        let $optionOffsetHeight = $option.offsetHeight;
        let $optionOffsetTop = $option.offsetTop;
        delta = $optionOffsetTop + $optionOffsetHeight - this.optionsListOffsetHeight;
      }
      if (delta > 0) {
        this.optionsList.scrollTop = delta;
      } else {
        this.optionsList.scrollTop = 0;
      }
    }
  }

  renderOptions(options, optGroupDisabled = false) {
    let { select, optionLabelPath, optionComponent, highlightedOption, onOptionClick } = this.props;
    return options.map((option, index) => {
      let optionIndex = getOptionIndex(this.props.options, option);
      if (isOptGroup(option)) {
        return (
          <div
            key={index}
            data-group-index={optionIndex}
            className={cx('PowerSelect__OptGroup', {
              'PowerSelect__OptGroup--disabled': !!option.disabled,
            })}
          >
            <div className="PowerSelect__OptGroup__Label">{option.label}</div>
            {this.renderOptions(option.options, option.disabled)}
          </div>
        );
      }
      return (
        <Option
          key={index}
          optionIndex={optionIndex}
          option={option}
          select={select}
          disabled={optGroupDisabled}
          optionLabelPath={optionLabelPath}
          optionComponent={optionComponent}
          isHighlighted={option === highlightedOption}
          onOptionClick={() => {
            onOptionClick(option);
          }}
        />
      );
    });
  }

  render() {
    let { options } = this.props;
    return (
      <div className="PowerSelect__Options" ref={optionsList => (this.optionsList = optionsList)}>
        {this.renderOptions(options)}
      </div>
    );
  }
}