This gist shows an idea on how to expose a public api for a ReactJS component to a Non-ReactJS host page.

MyComponent.jsx

'use strict';
/**
 * This is the actual root component that we want to either use in 
 * the context of a bigger ReactJS app or as a top level component used on a 
 * traditional Non-ReactJS host page. In the second case we want the component 
 * to expose a public API.
 */

var React = require('React');

var MyComponent = React.createClass({
    render() {
        return(<p>Hello {this.props.username}!</p>);
    },
    
    _show(msg) {
        console.log(msg);
    },

    api() {
        var that = this;
        return {
            show(msg) {
                that._show(msg);
            }
        };
    }
});

module.exports = MyComponent;

MyComponentLibWrapper.jsx

'use strict';
/**
 * When building as a top-level library component that should be rendered 
 * on a Non-ReactJS host page, this wrapper module will be the entry point 
 * of our build process.
 * 
 * The build process entering on this level will generate the 
 * ``react.mycomponent.lib.min.js`` file that can be requested in the browser.
 */

var React = require('React');
var MyComponent = require('./MyComponent');

module.exports = {
    render(domId, data) {
        return (
            function (component) {
                return component.api();
            }(
                React.render(
                    <MyComponent username={data.username} />,
                    document.getElementById(domId)
                )
            )
        );
    }
};

some-page.html

<div id="reactjs-canvas"></div>

<script type="text/javascript" src="./react.mycomponent.lib.min.js"></script>

<script type="text/javascript">
    /**
     * We call the ``render()`` method on the wrapper (probably render is a bad name) and
     * in return get the api object from ``MyComponent``.
     */
    var myComponent = MyComponentLibWrapper.render('reactjs-canvas', { username: 'foobar' });
    myComponent.show('I am logging something from outside via the public api.');
</script>