Simple countdown timer for React.js

CountdownTimer.js

import React, { Component } from 'react';

class CountdownTimer extends Component {
  state = {
    time: 30
  }

  componentDidMount() {
    this.startTimer();
  }

  componentWillUnmount() {
    this.stopTimer();
  }

  startTimer = () => {
    clearInterval(this.interval);
    this.setState({ time: 30 })
    this.interval = setInterval(() => {
      const { time } = this.state;
      if (time > 0) {
        this.setState({ time: time - 1 })
      } else {
        this.stopTimer();
      }
    }, 1000)
  }

  stopTimer = () => {
    const { time } = this.state;
    console.log(`Você parou em ${time} segundos`)
    clearInterval(this.interval);
  }

  render() {
    const { time } = this.state;
    return (
      <div>
        <span>
          { `Tempo restante: ${time} segundos` }
        </span>
        <div>
          <button type='button' onClick={ this.startTimer }>
            Iniciar Timer
          </button>
        </div>
        <div>
          <button type='button' onClick={ this.stopTimer }>
            Parar Timer
          </button>
        </div>
      </div>
    );
  }
}

export default CountdownTimer;