example.js

const InputBox = React.createClass({
  getInitialState: function() {
    return {data: [], interval: undefined};
  },
  componentDidMount: function() {
    const inverval = setInterval(this.update, 5000);
    this.setState({inverval});
  },
  componentWillUnmount: function() {
    clearInterval(this.state.inverval);
    this.setState({interval:undefined});
  },
  update: function(){
    const {data} = this.state;
    fetch('http://localhost:8181/data')  
    .then((response) => {
        if(response.ok){
          this.setState({data: response.json()})
        }else{
          console.log(response);
        }
    })
    .catch(function(error) {
      console.log(error.message);
    });
  },
  render: function() {
    return (
      <div className={"commentBox"}>
        <div>
          <div>
            <input />
          </div>
          <button>Enviar</button>
        </div>
        <div>
          {this.state.data.map((data)=>{
            return (<p>{data}</p>);
          })}
        </div>
      </div>
    );
  }
});

ReactDOM.render(
  <InputBox />,
  document.getElementById('contenido')
);