ESPTrainer/imports/ui/Square.jsx

import React, { Component, PropTypes } from 'react';
import './styles/Square';

export default class Square extends Component {
	render() {
		const classes = classNames('square', this.props.color, { 'highlighted': this.props.highlighted });
		return (
				<button className={classes} style={this.style}
						onClick={this.props.click} />
		);
	}
}

Square.propTypes = {
	color: PropTypes.string.isRequired,
	click: PropTypes.func,
	highlighted: PropTypes.bool
};