javascript ArrayGroupBy

/**
 * 数组按指定字段排序
 * @param itemlist
 * @param gby
 * @param keyName
 * @param valueName
 * @returns {Array}
 * @constructor
 */
function ArrayGroupBy (itemlist, gby, keyName = 'key', valueName = 'value') {
  var setGroupObj = function (noteObj, rule, gby, gIndex, maxIndex) {
    var gname = rule[gby[gIndex]];
    if (gIndex == maxIndex) {
      if (noteObj[gname] == undefined)
        noteObj[gname] = [];
      if (noteObj[gname].indexOf(rule) < 0) {
        noteObj[gname].push(rule);
      }
    }
    else {
      if (noteObj[gname] == undefined) {
        noteObj[gname] = {};
      }
      setGroupObj(noteObj[gname], rule, gby, gIndex + 1, maxIndex);
    }
  }
  
  var noteObj = {};
  for (var i = 0; i < itemlist.length; i++) {
    setGroupObj(noteObj, itemlist[i], gby, 0, gby.length - 1);
  }
  
  var getSubInfo = function (note, p, gIndex, maxIndex) {
    var newobj = {}
    newobj[keyName] = p;
    newobj[valueName] = [];
    if (gIndex == maxIndex) {
      for (var k in note[p]) {
        newobj[valueName].push(note[p][k]);
      }
    }
    else {
      for (var k in note[p]) {
        newobj[valueName].push(getSubInfo(note[p][k], k, gIndex + 1, maxIndex));
      }
    }
    return newobj;
  }
  var myobj = [];
  for (var p in noteObj) {
    myobj.push(getSubInfo(noteObj, p, 0, gby.length - 1));
  }
  return myobj;
}