src/basis/tracker.js
function getEventList(selector){
  var selectorStr = stringifyPath(selector);

  if (hasOwnProperty.call(selectorMap, selectorStr))
    return selectorMap[selectorStr];

  var eventList = selectorMap[selectorStr] = [];

  eventList.selectorStr = selectorStr;
  eventList.selector = selector;

  return eventList;
}
function getEventList(selector){
  var selectorStr = stringifyPath(selector);

  if (hasOwnProperty.call(selectorMap, selectorStr))
    return selectorMap[selectorStr];

  var eventList = selectorMap[selectorStr] = [];

  eventList.selectorStr = selectorStr;
  eventList.selector = selector;

  return eventList;
}
function getEventList ( selector ) { var selectorStr = stringifyPath ( selector ) ; if ( hasOwnProperty . call ( selectorMap , selectorStr ) ) return selectorMap [ selectorStr ] ; var eventList = selectorMap [ selectorStr ] = [ ] ; eventList . selectorStr = selectorStr ; eventList . selector = selector ; return eventList ; }
if there is no such selector in the `selectorMap`, creates empty array
@param {string} selector
@private
@return {Array}
if there is no such selector in the selectorMap creates empty array