(function() {

  window.main = function() {
    /* obtain a reference to the SVG
    */
    var vis;
    vis = d3.select('svg');
    /* when the user clicks the SVG
    */
    return vis.on('click', function() {
      /* retrieve mouse coordinates
      */
      var p;
      p = d3.mouse(this);
      /* create a new circle at point p
      */
      return vis.append('circle').attr('class', 'node').attr('r', 20).attr('cx', p[0]).attr('cy', p[1]);
    });
  };

}).call(this);