text: import React, {PureComponent, unstable_AsyncMode} from 'react';
  import {flushSync, render, unstable_deferredUpdates} from 'react-dom';
  import _ from 'lodash';
  import Charts from './Charts';
  import Clock from './Clock';
  import './index.css';
  
  let cachedData = new Map();
  
  class App extends PureComponent {
    state = {
      value: '',
      strategy: 'sync',
      showDemo: true,
      showClock: false,
    };
  
    // Random data for the chart
    getStreamData(input) {
      if (cachedData.has(input)) {
        return cachedData.get(input);
      }
      const multiplier = input.length !== 0 ? input.length : 1;
      const complexity =
        (parseInt(window.location.search.substring(1), 10) / 100) * 25 || 25;
      const data = _.range(5).map(t =>
        _.range(complexity * multiplier).map((j, i) => {
          return {
            x: j,
            y: (t + 1) * _.random(0, 255),
          };
        })
      );
      cachedData.set(input, data);
      return data;
    }
  
    componentDidMount() {
      window.addEventListener('keydown', e => {
        if (e.key.toLowerCase() === '?') {
          e.preventDefault();
          this.setState(state => ({
            showClock: !state.showClock,
          }));
        }
      });
    }
  
    handleChartClick = e => {
      if (this.state.showDemo) {
        if (e.shiftKey) {
          this.setState({showDemo: false});
        }
        return;
      }
      if (this.state.strategy !== 'async') {
        this.setState(state => ({
          showDemo: !state.showDemo,
        }));
        return;
      }
      if (this._ignoreClick) {
        return;
      }
      this._ignoreClick = true;
  
      // TODO: needing setTimeout here seems like a React bug.
      setTimeout(() => {
        unstable_deferredUpdates(() => {
          this.setState({showDemo: true}, () => {
            this._ignoreClick = false;
          });
        });
      });
    };
  
    debouncedHandleChange = _.debounce(value => {
      if (this.state.strategy === 'debounced') {
        flushSync(() => {
          this.setState({value: value});
        });
      }
    }, 1000);
  
    renderOption(strategy, label) {
      const {strategy: currentStrategy} = this.state;
      return (
        <label className={strategy === currentStrategy ? 'selected' : null}>
          <input
            type="radio"
            checked={strategy === currentStrategy}
            onChange={() => this.setState({strategy})}
          />
          {label}
        </label>
      );
    }
  
    handleChange = e => {
      const value = e.target.value;
      const {strategy} = this.state;
      switch (strategy) {
        case 'sync':
          this.setState({value});
          break;
        case 'debounced':
          this.debouncedHandleChange(value);
          break;
        case 'async':
          // TODO: needing setTimeout here seems like a React bug.
          setTimeout(() => {
            unstable_deferredUpdates(() => {
              this.setState({value});
            });
          });
          break;
        default:
          break;
      }
    };
  
    render() {
      const Wrapper =
        this.state.strategy === 'async' ? unstable_AsyncMode : 'div';
      const {showClock} = this.state;
      const data = this.getStreamData(this.state.value);
      return (
        <div className="container">
          <div className="rendering">
            {this.renderOption('sync', 'Synchronous')}
            {this.renderOption('debounced', 'Debounced')}
            {this.renderOption('async', 'Asynchronous')}
          </div>
          <input
            className={'input ' + this.state.strategy}
            placeholder="longer input → more components and DOM nodes"
            defaultValue={this.state.input}
            onChange={this.handleChange}
          />
          <Wrapper>
            <div className="demo" onClick={this.handleChartClick}>
              {this.state.showDemo && (
                <Charts data={data} onClick={this.handleChartClick} />
              )}
              <div style={{display: showClock ? 'block' : 'none'}}>
                <Clock />
              </div>
            </div>
          </Wrapper>
        </div>
      );
    }
  }
  
  const container = document.getElementById('root');
  render(<App />, container);
  