How to compare time units in JS

//时间比较（yyyy-MM-dd）
function compareDate(startDate, endDate) {
  var arrStart = startDate.split("-");
  var startTime = new Date(arrStart[0], arrStart[1], arrStart[2]);
  var startTimes = startTime.getTime();
  var arrEnd = endDate.split("-");
  var endTime = new Date(arrEnd[0], arrEnd[1], arrEnd[2]);
  var endTimes = endTime.getTime();
  if (endTimes<startTimes) {
    alert("结束时间不能小于开始时间");
    return false;
  }
  return true;
}
//时间比较（yyyy-MM-dd HH:mm:ss）
function compareTime(startTime,endTime) {
  var startTimes = startTime.substring(0, 10).split(&#39;-&#39;);
  var endTimes = endTime.substring(0, 10).split(&#39;-&#39;);
  startTime = startTimes[1] + &#39;-&#39; + startTimes[2] + &#39;-&#39; + startTimes[0] + &#39; &#39; + startTime.substring(10, 19);
  endTime = endTimes[1] + &#39;-&#39; + endTimes[2] + &#39;-&#39; + endTimes[0] + &#39; &#39; + endTime.substring(10, 19);
  var thisResult = (Date.parse(endTime) - Date.parse(startTime)) / 3600 / 1000;
  if (thisResult < 0) {
    alert("endTime小于tartTime！");
  } else if (thisResult > 0) {
    alert("endTime大于tartTime！");
  } else if (thisResult == 0) {
    alert("endTime等于tartTime！");
  } else {
    return &#39;异常&#39;;
  }
}