code: function capture(target, eventType, callback) {
      if (target.addEventListener) {
        target.addEventListener(eventType, callback, true);
        return {
          remove: function remove() {
            target.removeEventListener(eventType, callback, true);
          }
        };
      } else {
        if (process.env.NODE_ENV !== 'production') {
          console.error('Attempted to listen to events during the capture phase on a ' + 'browser that does not support the capture phase. Your application ' + 'will not receive some events.');
        }
        return {
          remove: emptyFunction
        };
      }
    }
docs: Listen to DOM events during the capture phase.
  
  @param {DOMEventTarget} target DOM element to register listener on.
  @param {string} eventType Event type, e.g. 'click' or 'mouseover'.
  @param {function} callback Callback function.
  @return {object} Object with a `remove` method.