React Base Fiddle (JSX)

Starting point for creating JSFiddles with React.

HTML

<script src="https://unpkg.com/react@16/umd/react.development.js"></script>
<script src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>
<div id="container">
    <!-- This element's contents will be replaced with your component. -->
</div>

CSS

.wrapper-progressbar {
  flex: 1;
}

progress {
  width: 100%;
  background-image:
    linear-gradient(
      90deg,
      rgba(255,0,0,0.1),
      rgba(255,0,0,0.1) 30%,
      rgba(0,255,0,0.1) 30%,
      rgba(0,255,0,0.1) 70%, 
      rgba(255,0,0,0.1) 70%);
  border: 0;
  height: 2em;
  border-radius: 9px;
  box-shadow: 0 2px 3px rgba(0, 0, 0, 0.25) inset;
}

progress[value]::-webkit-progress-bar {
  width: 100%;
  background: transparent;
  background-image:
    -webkit-linear-gradient(
      left,
      rgba(255,0,0,0.1),
      rgba(255,0,0,0.1) 30%,
      rgba(0,255,0,0.1) 30%,
      rgba(0,255,0,0.1) 70%,
      rgba(255,0,0,0.1) 70%);
  border: 0;
  height: 2em;
  border-radius: 9px;
  box-shadow: 0 2px 3px rgba(0, 0, 0, 0.25) inset;
}

progress[value] {
  background-color: transparent;
  border-radius: 5px;
  box-shadow: 0 2px 3px rgba(0, 0, 0, 0.25) inset;
  position: relative;
  /* Reset the default appearance */
  -webkit-appearance: none;
  -moz-appearance: none;
  appearance: none;
  /* Get rid of default border in Firefox. */
  /*border: none;*/
}

progress[value]::-moz-progress-bar { /* Firefox */
  border-radius: 2px;
  background-size: 65px, 100%, 100%;
  background-color: transparent;
  background-image:
    -moz-linear-gradient(
      135deg,
      transparent 33%,
      rgba(0, 0, 0, 0.1) 33%,
      rgba(0, 0, 0, 0.1) 66%,
      transparent 66%
    ),
    -moz-linear-gradient(
      top,
      rgba(255, 255, 255, 0.25),
      rgba(0, 0, 0, 0.25)
    ),
    -moz-linear-gradient(
      left,
      rgba(255,0,0,0.8),
      rgba(255,0,0,0.8) 37.5%,
      rgba(0,255,0,0.8) 37.5%,
      rgba(0,255,0,0.8) 87.5%,
      rgba(255,0,0,0.8) 87.5%
    );
}

progress[value]::-webkit-progress-value { /* Chrome */
  border-radius: 2px;
  background-size: 65px, 100%, 100%;
  background-color: transparent;
  background-image:
    -webkit-linear-gradient(
      135deg,
      transparent 33%,
      rgba(0, 0, 0, 0.1) 33%,
      rgba(0, 0, 0, 0.1) 66%,
     ...

Babel + JSX

const Progressbar = ({percent, min, max}) => {

  let styleProgress = {  backgroundImage:
    `linear-gradient(
      90deg,
      rgba(255,0,0,0.1),
      rgba(255,0,0,0.1) ${min}%,
      rgba(0,255,0,0.1) ${min}%,
      rgba(0,255,0,0.1) ${max}%,
      rgba(255,0,0,0.1) ${max}%)`
  };

  return(
      <div className="wrapper-progressbar">
        <progress style={styleProgress} max="100" value={percent}>
        </progress>
      </div>
  );
};

class Hello extends React.Component {
  constructor (props) {
    super(props);
    this.state = {percent: "80"};
    this.handleRefreshTimeout = this.handleRefreshTimeout.bind(this);
  }

componentDidMount() {
  // after render()
  setTimeout(() => {
    this.handleRefreshTimeout(1000);
  }, 1000);
}

  handleRefreshTimeout(timeout = 1000) {
    switch(this.state.percent) {
      case '80':
        this.setState({percent: '50'});
        break;
      case '50':
        this.setState({percent: '20'});
        break;
      case '20':
        this.setState({percent: '80'});
        break;
      default:
        this.setState({percent: '20'});
    }
    
    setTimeout(() => {
      this.handleRefreshTimeout(timeout);
    }, timeout)
  }


  render() {
    return (
    <div>The value is: {this.state.percent}
    <Progressbar min="30" max="70" percent={this.state.percent} /></div>
    );
  }
}

ReactDOM.render(
  <Hello />,
  document.getElementById('container')
);