如何在reactjs组件中使用普通javascript?

我使用chartist.js,并且在reactjs组件中使用chartist。 我指的是这个 http://gionkunz.github.io/chartist-js/examples.html#simple-pie-chart

JSITS.JS:

var Chartist = {
    version:'0.9.5' 
}

(function (window, document, Chartist) {

var options = {
  labelInterpolationFnc: function(value) {
    return value[0]
  }
};

var responsiveOptions = [
  ['screen and (min-width: 640px)', {
    chartPadding: 30,
    labelOffset: 100,
    labelDirection: 'explode',
    labelInterpolationFnc: function(value) {
      return value;
    }
  }],
  ['screen and (min-width: 1024px)', {
    labelOffset: 80,
    chartPadding: 20
  }]
];

})();

ReactJS组件:

import React, { Component } from 'react';

var data = {
  labels: ['Bananas', 'Apples', 'Grapes'],
  series: [20, 15, 40]
};

showPieChart(data){
     new Chartist.Pie('.ct-chart', data, options, responsiveOptions);
}

class Chart extends Component {

  render(){
    return(
      <div>
          <div className="center">
              {showPieChart}
          </div>
      </div>

    )}

}

export default Chart;

网页上不显示任何内容。如何访问香草JavaScript内部的反应组件。