active.js

import {Transition} from "./transition/index";
import {SCHEDULED} from "./transition/schedule";

var root = [null];

export default function(node, name) {
  var schedules = node.__transition,
      schedule,
      i;

  if (schedules) {
    name = name == null ? null : name + "";
    for (i in schedules) {
      if ((schedule = schedules[i]).state > SCHEDULED && schedule.name === name) {
        return new Transition([[node]], root, name, +i);
      }
    }
  }

  return null;
}