Example.js

class Example extends Component {
  componentWillReceiveProps(nextProps) {
    // Only update state if needed.
    if (nextProps.startTime !== this.state.startTime) {
      // Change state using new prop value.
      this.setState({
        seconds: toSeconds(this.props.startTime)
      })
    }
  }

  handleChange = value => {
    // The value entered by user is valid, let's dispatch some potentially
    // heavy redux action. This will then set the state in
    // componentWillReceiveProps().
    if (isValid(value)) {
      this.props.saveItem(value)
    }
    // Otherwise, just update state, this should be fast.
    else {
      this.setState({
        seconds: toSeconds(value)
      })
    }
  }

  render() {
    return <Input value={ this.state.seconds } onChange={ this.handleChange }/>
  }
}