React Component for Popper.js v1 that takes the reference as its first child and the popper as its second child (a la react-tether)

Popper.jsx

import React, { Component, PropTypes } from 'react';
import PopperJS from 'popper.js';

export default class Popper extends Component {
  state = {}

  update = () => {
    if (this.popperInstance) {
      this.popperInstance.scheduleUpdate();
    }
  }

  componentDidMount() {
    this.popperInstance = new PopperJS(this.content, this.popper, {
      placement: 'top',
      modifiers: {
        arrow: { element: this.arrow },
        applyStyle: { enabled: false },
      },
      onCreate: (data) => this.setState({data}),
      onUpdate: (data) => this.setState({data})
    });
  }

  componentWillUnmount() {
    this.popperInstance.destroy();
  }

  getPopperStyle(data) {
    if (!data) { return {}; }
    const left = Math.round(data.offsets.popper.left);
    const top = Math.round(data.offsets.popper.top);
    const transform = `translate3d(${left}px, ${top}px, 0)`;
    return {
      position: data.offsets.popper.position,
      transform,
      WebkitTransform: transform,
      top: 0,
      left: 0
    };
  }
  
  getArrowStyle(data) {
    if !(data) { return {}; }
    const left = Math.round(data.offsets.arrow.left);
    const top = Math.round(data.offsets.arrow.top);
    return { position: 'absolute', top, left };
  }

  render() {
    const { children, arrow } = this.props;
    return (
      <div>
        <div
          ref={(el) => (this.content = el)}
          className='popper-content'
        >
          {this.props.children[0]}
        </div>
        <div
          ref={(el) => (this.popper = el)}
          data-placement={this.state.data && this.state.data.placement}
          className='popper'
          style={this.getPopperStyle(this.state.data)}
        >
          {this.props.children[1]}
          {arrow && <div
            ref={(el) => (this.arrow = el)}
            className='arrow'
            style={this.getArrowStyle(this.state.data)}
          />}
        </div>
      </div>
    );
  }
}