4 methods are identicalArray.prototype.map.call(dataSet, function)[].map.call(dataSet, function)dataSet.map(function)dataSet.map.call(dataSet, function) 아래 두 개는 dataSet으로 정확히 array를 넣어줘야함 [].map.call() VS Array.prototype.map.call()?Why would one be preferred over the other? [].map.call(...) Array.prototype.map.call(...) Doing a quick test in jsPerf shows the Array.prototype way is more perform..