Sorting some data with ReactJS

gistfile1.js

var PayTable = React.createClass({
    getInitialState: function() {
        return {
            sortDirection: 'descending',
            data: this.props.payYears.sort(sortDescending)
        };
    },
    sortData: function() {
        if(this.state.sortDirection==='descending') {
            this.setState({ 
                sortDirection: 'ascending',
                data: this.props.payYears.sort(sortAscending)
            });
        } else {
            this.setState({ 
                sortDirection: 'descending',
                data: this.props.payYears.sort(sortDescending)
            });
        }
    },
    render: function() {
        return (
            <table className="table table-striped">
                <thead>
                    <tr>
                        <th onClick={this.sortData}
                            className={this.state.sortDirection}>
                            Year
                        </th>
                        <th>All</th>
                        <th>Full-time</th>
                        <th>Part-time</th>
                    </tr>
                </thead>
                <tbody>
                    {this.state.data.map(function(payYear) {
                      return <PayRow key={payYear.year} payYear={payYear} />;
                    })}
                </tbody>
            </table>
        );
    }
});