How to add or remove a className on event in ReactJS?

The list of classes can be derive from the state of the component. For example:

var Component = React.createClass({
  getInitialState: function() {
    return {
      clicked: false
    };
  },

  handleClick: function() {
    this.setState({clicked: true});
  },

  render: function() {
    var className = this.state.clicked ? 'click-state' : 'base-state';
    return <div className={className} onClick={this.handleClick}>click here</div>;
  }
});

Calling this.setState will trigger a rerender of the component.