Edit in JSFiddle

Result
JavaScript 1.7
HTML

/** @jsx React.DOM */
/* global React, Backbone, $ */

var MyWidget = React.createClass({
  handleClick: function() {
    alert('Hello!');
  },
  render: function() {
    return (
      <a href="#" onClick={this.handleClick}>Do something!</a>
    );
  }
});

var MyView = Backbone.View.extend({
  el: 'body',
  template: '<div class="widget-container"></div>',
  render: function() {
    this.$el.html(this.template);
    React.renderComponent(new MyWidget(), this.$('.widget-container').get(0));
    return this;
  }
});

new MyView().render();

<script src="http://fb.me/react-js-fiddle-integration.js"></script>

<body>
</body>