state animation for React.js using d3.js and some underscore.js sugar

gistfile1.txt

  animate: function(attr, targetValue, duration, ease) {
    var cmp = this;

    var interpolator;
    if (_.isFunction(targetValue)) {
      interpolator = targetValue;
    } else {
      interpolator = d3.interpolate(this.state[attr], targetValue);
    }

    return d3.transition()
      .duration(duration || 500)
      .ease(ease || "cubic-in-out")
      .tween(attr, function() {
        return function(t) {
          cmp.setState(_.object([attr], [interpolator(t)]));
        };
      });
  },