flat-icon.js

const FlatIcon = ({ iconName }) => (
  <i className={`faticon-${iconName}`} />
)

FlatIcon.propTypes = {
  iconName: React.PropTypes.string.isRequired,
};

old.js

var FlatIcon = React.createClass({
  displayName: "FlatIcon",
  propTypes: {
    iconName: React.PropTypes.string.isRequired
  },
  render: function() {
    return React.createElement("i", {
      "className": "flaticon-" + this.props.iconName
    });
  }
});